It would seem that the computer boot process has been studied by us to the smallest detail: button - BIOS - operating system - login ... Have you ever thought about what is actually happening inside your computer at this time? Can you tell us step by step how a computer works? I’m sure not. Therefore, today we will conduct a short educational program - we will talk about how the computer actually boots.
This article examines the operation of Windows XP, in other systems, the process is naturally slightly different.
The power switch turns on.
The power supply performs a self-test. When all electrical parameters are normal, the PSU sends a Power Good signal to the processor. The time between power-up and signal disappearance is usually 0.1-0.5 seconds.
The microprocessor timer receives a Power Good signal.
On receipt of this signal, the timer stops sending the Reset signal to the processor, allowing it to turn on.
The CPU starts executing the ROM BIOS code.
The processor loads the ROM BIOS starting from the address FFFF: 0000. At this address, only the transition to the address of the real BIOS ROM code is registered.
The system performs an initial hardware test.
Each error that occurs at this stage is reported by certain sound codes (in the past by beeping, now it is probably more modern - by voice), since the video system has not yet been initialized.
The BIOS looks for adapters that may require their BIOS to boot.
The most typical case in this case is a video card. The boot routine scans the memory from C000: 0000 to C780: 0000 to search for the video ROM. This boots the systems of all adapters.
The ROM BIOS checks to shut it down or reboot.
Procedure two bytes at address 0000: 0472. Any value other than 1234h indicates a cold start.
If this is enabling the ROM the BIOS runs a full POST (Power On Self Test). If this is a reboot, then the memory check is excluded from the POST procedure.
The POST procedure can be divided into three components:
- The video test initializes the video adapter, tests the card and video memory, shows the configuration or errors that have occurred.
- BIOS identification shows firmware version, manufacturer and date.
- The memory test checks the memory chips and calculates the size of the installed memory.
Errors that may arise during the POST check can be divided into fatal and not very good :). In the second case, they are shown on the screen, but allow you to continue the boot process. It is clear that in the first case, the boot process stops, which is usually accompanied by a series of beep codes.
BIOS reads configuration information from CMOS.
A small area of memory (64 bytes) is powered by a battery on the motherboard. The most important thing for loading in it is the order in which the drives should be polled, which of them should be the first - a floppy drive, CD-ROM or hard drive.
If the first is the hard drive, the BIOS checks the very first sector of the drive for a Master Boot Record (MBR). The Boot Record in the first sector is checked for the drive.
Master Boot Record - first sector on cylinder 0, 0 head, 512 bytes in size. If it is found, it is loaded into memory at address 0000: 7C00, then it is checked for the correct signature - the last two bytes should be 55AAh. The absence of the MBR or these check bytes stops the boot process and issues a warning. The MBR itself consists of two parts - the partition loader, or Boot loader, the program that takes control when booting from that hard disk; partition table (partitions), which contains information about the logical disks available on the hard disk.
The correct MBR record is written to memory and control is transferred to its code.
The process of installing several operating systems on one computer usually replaces the original loader with its own program, which allows you to choose from which disk to boot the rest of the boot.
Next, Boot Loader checks the table of partitions in search of an active one. The bootloader then looks for a Boot Record on the very first sector of the partition.
In this case, Boot Record is another 512 bytes - a table with a description of the partition (the number of bytes in the sector, the number of sectors in the cluster, etc.) and the transition to the first file of the operating system (IO.SYS in DOS).
Operating system
Control is transferred to the operating system. How does it work, how does the download process go?
Boot Record is checked for correctness and if the code is found to be correct then the boot sector code is executed as a program.
Booting Windows XP is controlled by the NTLDR file located in the root directory of the system partition. NTLDR works in four steps:
- Initial loading phase
- System selection
- Determination of iron
- Choice of configuration
In the initial phase, NTLDR switches the processor to protected mode. It then loads the appropriate file system driver to work with files for any file system supported by XP.
If anyone has forgotten, then our favorite OS can work with FAT-16, FAT-32 and NTFS.
If there is BOOT.INI in the root directory, then its contents are loaded into memory. If it contains records about more than one operating system, NTLDR stops working - displays a menu with a choice and waits for user input for a certain period of time.
If there is no such file, NTLDR continues booting from the first partition of the first disk, usually C: \.
If in the process of selection the user has selected Windows NT, 2000 or XP, then pressing F8 is checked and the corresponding menu with boot options is displayed.
After every successful boot, XP creates a copy of the current combination of drivers and system settings known as Last Known Good Configuration. This collection can be used to boot if a new device has corrupted the operating system.
If the selected operating system is XP, then NTLDR finds and loads the DOS program NTDETECT.COM to determine the hardware installed in the computer.
NTDETECT.COM builds a list of components, which is then used in the HARDWARE key of the HKEY_LOCAL_MACHINE branch of the registry.
If the computer has more than one hardware profile, the program stops from the configuration selection menu.
After choosing the configuration, NTLDR starts loading the XP kernel (NTOSKRNK.EXE).
During the kernel boot process (but before initialization), NTLDR remains central to managing the computer. The screen is cleared and a white rectangle animation is shown at the bottom. In addition to the kernel, the Hardware Abstraction Layer (HAL.DLL) is also loaded so that the kernel can abstract itself from the hardware. Both files are located in the System32 directory.
NTLDR loads device drivers marked bootable. Having loaded them NTLDR transfers control of the computer further.
Each driver has a key at HKEY_LOCAL_MACHINE \ SYSTEM \ Services. If the Start value is equal to SERVICE_BOOT_START, then the device is considered bootable. For each such device, a dot is printed on the screen.
NTOSKRNL goes through two phases during the boot process - the so-called phase 0 and phase 1. The first phase initializes only that part of the microkernel and the executive subsystems that are required for the main services to work and continue the boot. At this stage, a graphical screen with a status bar is shown on the screen.
XP disables interrupts during phase 0 and enables them only before phase 1. HAL is called to prepare the interrupt controller. Memory Manager, Object Manager, Security Reference Monitor, and Process Manager are initialized. Phase 1 begins when the HAL prepares the system to handle device interrupts. If more than one processor is installed on the computer, they are initialized. All executive subsystems are reinitialized in the following order:
- Object Manager
- Executive
- Microkernel
- Security Reference Monitor
- Memory manager
- Cache Manager
- I / O Manager
- Process Manager
I / O Manager initialization starts the process of loading all system drivers. From the moment where NTLDR stopped, the drivers are loaded by priority.
Failure to load the driver can force XP to reboot and try to restore the Last Known Good Configuration.
The final task of Phase 1 of kernel initialization is to start the Session Manager Subsystem (SMSS). The subsystem is responsible for creating the user environment that provides the NT interface.
SMSS operates in user mode, but unlike other applications, SMSS is considered a trusted part of the operating system and a "native" application (uses only executive functions), which allows it to start the graphics subsystem and login.
SMSS loads win32k.sys, the graphics subsystem.
The driver switches the computer to graphics mode, SMSS starts all services that should automatically start at startup. If all devices and services have started successfully, the boot process is considered successful and the Last Known Good Configuration is created.
The download process is not considered complete until the user is logged into the system. The process is initialized by the WINLOGON.EXE file, run as a service and maintained by the Local Security Authority (LSASS.EXE), which displays the login dialog.
This dialog box appears approximately when the Services Subsystem starts the network service.
Many users of computer systems are so used to working in Windows XP that they do not want to change it to a more recent version of the operating system under any pretext.
However, XP itself, like the following versions of Windows operating systems, is susceptible to errors like "Unable to start HAL.dll", "File is damaged or missing", "File not found", etc. let's see how you can restore the system boot without drastic measures, such as reinstalling the operating system.
What is the file?
If we are talking about the file itself, then it will be quite difficult for an ordinary user to understand the principle of its functioning. In simple terms, the HAL.dll file in the Windows XP operating system is responsible for the interaction of software and hardware components. This is the so-called layer of software code at the hardware abstraction level. It hides at all levels some aspects of the hardware implementation - from hardware to software. This applies to all components present in the system. Then why, when loading the system, there are errors incomprehensible to many? What does the inscription "HAL.dll missing or damaged" mean on the monitor screen?
The Windows XP operating system is one of the most outdated operating systems. She is most susceptible to this kind of failure.
Main functions of HAL.dll
If we talk about the functionality, then it can be noted that this library is a kind of layer that allows users and software developers to use the application command to directly refer to a specific hardware component, not even taking into account the brand of the device, the name of the manufacturer, etc. In general, this is a universal bridge that allows the program to work on any equipment in a universal mode. Let's try to put it a little differently. By the principle of operation, the functionality of the HAL.dll library can be compared with DirectX.
Why am I getting the error "HAL.dll is missing or corrupt"?
Generally speaking, there are many reasons for this kind of error. The most common causes are damage to the memory strips and hard drive. In this case, you just need to perform diagnostics. Of course, we cannot exclude the possibility of infection with a virus that can change the structure of this file, as well as completely delete it from the hard disk of the computer. However, today we will not take into account such situations. It should be assumed that everything is in order with the hard disk in the computer, and there are no viruses on the computer. Thus, the error can be caused solely by software glitches.
System Restore
First of all, consider the situation when the system does boot. At the beginning of the boot process, a line may appear on a black screen that informs the user that the HAL.dll file is missing or damaged. In this case, the easiest solution would be to boot Windows XP in Safe Mode with Command Prompt. To do this, at the beginning of the boot process, you must use the F8 key, and then you need to select the appropriate section. When the command line appears, write the combination c: \ windows \ system32 \ restore \ rstrui.exe in it. Then you just need to follow the instructions on the screen. In many cases, this will correct the situation. But what if, even after performing this operation, a message appears about the absence of this boot element and the system does not boot at all?
Correcting incorrect entries in boot.ini
Some users are not even aware that this error is not necessarily associated with this particular library. Sometimes a similar problem is a consequence. The reason lies in incorrect entries in the boot.ini file that point to the volume partition that contains the operating system. Of course, you can use some programs for Windows XP, but first let's try to figure out how this can be done without third-party tools. First, we boot from any Windows XP installation disk, setting the CD / DVD-ROM as the priority boot device.
After that, click on the R button and go to the recovery console. Now you need to select the desired assembly of the Windows XP operating system. Enter the administrator password and use the bootcfg / rebuild command. Now we press "Enter". When a copy of Windows is found, add it to the download list and confirm the operation by pressing the Y button. Enter the identifier in the form of a Windows XP modification. Then we reboot and choose the boot option with the new source. The boot.ini file can then be found on the system. Open it with the standard Notepad program and delete the wrong download path.
Remedy with the console
The above system recovery options do not always work. The reason for this problem may lie in the absence or damage of the desired file. By default, it should be located on the system drive at Windows \ System32 \ HAL.dll. Here again we need a boot disk and a recovery console. Only now the task is to find the original file on the disk and copy it to the system partition of the hard disk. It should be noted right away that such operations are possible only in the XP operating system; with Windows 7 or 8, such tricks will not work. Suppose your computer has a drive letter E.
The file is located on disk in the i386 folder. In order to make sure that this file is actually present, you must use the command E: \ i386> dir. The file name may not correspond to the original and is designated as HAL.dl_. In this case, you need to unpack the packed CAB archive. To do this, use the expand e: i386hal.dl_ c: \ windows \ system32 command. There must be a space in front of the C drive. Of course, you can unpack the file directly to the system disk, and then just copy it to the desired location. But what if the replacement and copying can be done directly? After that, the system should boot normally without any problems.
How to fix the situation using third-party programs?
There are specialized applications that can be used to fix errors related to a corrupt or missing HAL.dll file. Like Acronis Recovery Expert, Acronis Disk Director, Bootice. These programs, in principle, differ little from each other. You need to download them from a flash drive or optical media. They use the same principles in their work. Another thing is that the user does not have to enter specific commands. The menu of such applications is completely concretized. Such programs are designed to recover damaged and lost data, as well as entire partitions of hard drives.
As you probably already noticed, all of these applications are generic programs that suit literally all occasions. In some way they can help even an inexperienced user. Although the fact that an ordinary user who does not possess certain skills and abilities will use these programs raises great doubts. Most of them, unfortunately, do not even try to grasp the essence of the issue, and immediately rush to reinstall the operating system. And in vain, because when reinstalling the operating system, such errors may occur that the installation will never be completed. As a result, you risk getting a completely inoperative system.
Conclusion
Using special data recovery software is definitely a good thing. However, there is no firm assurance that the correct DLL file will actually be fully restored. For this reason, despite the simplicity of working with these applications and their almost complete automation, it is still better to use the standard methods of restoring the system boot. Of course, they are more complicated and take more time, but in this case you can be sure that the system will be fully operational.
But still, in some cases, when DLL errors occur due to other software failures, the use of these programs can be quite justified. But if the problem lies in the malfunctioning of the RAM or hard disk, then you are unlikely to be able to fix this problem at the software level. For a start, it is better to go through full testing, and, if necessary, replace some of the elements.
There are many reasons why Windows XP does not load. Most often, the problem is accompanied by a text explanation on a black background. But sometimes even it may not be there. The article will discuss the most popular errors and operating system failures, as well as ways to eliminate them.
Possible problems
Among the most common errors are the following: Bootmgr is missing, NTLDR is missing, BSOD and many others. In the first case, the problem is in the corruption of the bootloader files. The second failure indicates a violation of the integrity of the registry entries. BSOD is one of the names of the blue screen of death. There are also other failures, the complete list of which would take dozens of pages.
But solutions for many faults are universal. For example, most minor problems with a production system can be resolved with a reboot. Of course, there are often exceptions to this rule, but it has a right to life.
Next, we will consider universal ways to get rid of situations when Windows XP does not start. If you cannot determine the cause or error code, then simply follow each one in order. One of them will definitely help. If the problem is known, then review the appropriate section of the article.
Method 1: Last Known Good Configuration
When Windows XP fails to start normally several times, the boot menu will open. It contains several options for emergency system start. For a start, you should choose "The last good one ..." In this mode, the system files will be partially rolled back to the state when the PC was functioning in normal mode.
Important: If the boot options menu does not start automatically, you must open it manually. To do this, restart your PC and press F8 repeatedly.
If this option of turning on the computer turned out to be successful, then everything is in order with Windows, there was a one-time failure. On this, the problem can be considered solved, subsequent launches will occur in standard mode. They don't need the same setup.
Otherwise, the failure is not so easy to fix. Then go to the next solution to the problem.
Method 2: Recover from Safe Mode
Now let's consider a short version of calling this function. Expand the complete list of items in Start. Next go to "Standard - Service"... And from there run the element "System Restore".
Then just follow the directions on the screen.
Note: When rolled back, user data will not be affected. However, some programs may be uninstalled and the settings may be canceled. Strictly speaking, this is what the recovery procedure is all about.
Method 3: Live CD
Live CD is called a disc with a system that does not require installation. It is immediately ready for use. Live Image allows you to perform emergency recovery and data backup on a computer or laptop with non-working Windows.
First you need to find a suitable Live CD to burn to a disc or flash drive. This will require another computer with Internet access.
Now connect the media to the faulty computer and perform the recovery using standard Live CD tools. You can also try to replace the following system files: Boot.ini, NTLDR, Ntdetect. They are responsible for the bootloader and other important Windows components.
Method 4: reinstall Windows XP
Failure in the previous three cases indicates that the corruption of the system files is most likely critical. They are not recoverable by standard. Only remains.
It requires the creation of a bootable disk with an operating system image. This procedure is no different from burning a Live CD. The Windows image is not available for download from Microsoft servers, so first, find a suitable assembly on the Internet. The easiest way to transfer it to a disc is with UltraISO, you can also use a USB flash drive.
When the recording is complete, you need to set the BIOS to boot from removable media. This is done in the Boot section. There, find the Boot Priority item, put the desired device in the first place. 
Then go back to the main section and exit with saving the settings. Now restart your computer. The installation procedure will start. You need to format the disk completely.
Important: if you do not want to lose data, then first transfer it to removable media by booting via Live CD.
Using a Windows Boot Floppy
The first thing to refer to when a problem occurs during system startup is the boot floppy. It can help if the active partition of the hard disk or the files required to boot Windows are damaged.
In order to create a bootable Windows diskette, insert the floppy disk into the disk drive of the machine with the Windows XP operating system working correctly and configured in a similar way, open the My Computer window, click on the diskette icon and select the Format "(Format). In the Format dialog box, keep the default settings and click the Start button. Upon completion of formatting, close the window in order to return to "My Computer", double-click on the shortcut of the C drive and copy three files from its root directory to the floppy disk:
Boot.ini
NTLDR
Ntdetect.com
Now insert the created boot floppy disk into the floppy drive of the computer with the damaged system and click to restart the computer. When started from this floppy, the system will try to boot, ignoring the active hard disk partition and boot files.
Using the Last Known Good Configuration option)
You can also try starting the system using the Last Known Good Configuration option, which will undo any changes that caused problems in the CurrentControlSet registry key, which is responsible for determining hardware parameter values and installed drivers. The Last Known Good Configuration option will replace the contents of the specified registry key with the data from the backup that was used when the OS was last successfully started.
Restart your computer by clicking. When you see the message “Please select the operating system to start” or hear a single beep, press the key to launch the Windows Advanced Options menu. Select Last Known Good Configuration and press.
Note that you only have one attempt to restore the last known good configuration. In other words, if the option did not help to fix the system boot problem, then the backup is also corrupted.
Using System Restore
Another useful tool for troubleshooting Windows XP boot problems is System Restore. It runs in the background as a service to continually check critical system components for changes. Before changing any parameter, the service immediately creates a backup copy of it and a restore point. In addition, by default, checkpoints are generated every 24 hours.
To use the System Restore utility, restart your computer by clicking. When you see the message “Please select the operating system to start” or hear a single beep, press the key to launch the Windows Advanced Options menu. Select Safe Mode and press.
After booting Windows XP in Safe Mode, click the Start button and go to the Programs | Standard | Service | System Restore (All Programs | Accessories | System Tools | System Restore). In safe mode, only the option "Restore an earlier state of the computer" is available, since it is already selected by default, just click "Next" (Next). The Recovery Wizard will then prompt you to select a checkpoint and start the recovery procedure.
Using the Recovery Console
Windows XP boot problems of a more complex nature require, respectively, a more serious approach. The Windows XP Bootable CD contains the useful Recovery Console tool.
To start the system from a bootable Windows XP CD, insert it into the CD-ROM and click to restart the computer. Once the download starts, simply follow the directions that will allow you to select the core files to run Setup. At the Welcome To Setup screen shown in Figure A, press the R key to launch the Recovery Console.
The Recovery Console menu screen appears (Figure B). The folder with the operating system files is displayed here and a request to select the operating system that you want to enter. Press the corresponding number key, and then enter the administrator password. You now have access to the command line of the Recovery Console.
Rice. B
Fixing a damaged Boot.ini file
At the beginning of the Windows XP boot process, Ntldr uses the Boot.ini file to determine the location of the operating system files and whether options are available to continue booting. Therefore, if the Boot.ini file is damaged, Windows XP cannot start correctly.
If the system does not boot due to a damaged Boot.ini file, you can use the Bootcfg tool in the Recovery Console. Of course, to do this, you will have to start the system from a bootable CD and use the Recovery Console, as described in point 4.
To run the Bootcfg command, enter in the command line of the Operations Console:
Bootcfg / parameter
Where / parameter- one of the options below.
Parameters and Description
/ Add- scans the disk for all installed versions of Windows and allows you to add new OS identifiers to the Boot.ini file.
/ Scan- scans the disk for all installed versions of Windows.
/ List- displays each entry in the Boot.ini file.
/ Default- assigns the identifier set by default in the boot menu of the operating system as the main one.
/ Rebuild- completely recreates the Boot.ini file. The user has the ability to confirm each step.
/ Redirect- allows in administration mode without a monitor to redirect the download operation to a special port. Has two sub-parameters:
|
.
/ Disableredirect- Disables redirection.
Fixing a damaged hard disk boot sector
The boot sector is a small section of the hard disk that contains information about the operating system file system (NTFS or FAT32), as well as a very small program written in machine code that helps during the OS boot process.
If the system does not start due to a damaged boot sector, you can use the FixBoot tool in the Recovery Console. To do this, you will have to start the system from a bootable CD and use the Recovery Console, as described in point 4.
To run the FixBoot command, enter in the command line of the Management Console:
Fixboot:
Where
- the letter of the drive for which you want to create a new boot partition.
Fixing a damaged master boot record
The Master Boot Record occupies the first sector of the hard disk to start the Windows boot procedure. It contains the partition table and a small program called the master boot record that is responsible for placing the active or boot sector in the partition table. Once placed in the table, the boot sector begins to start Windows. If the master boot record is damaged, the active sector will not be able to start the system.
To fix this problem, the Fixmbr tool is provided in the Recovery Console. Start the system from a bootable CD and activate the Recovery Console as described in point 4.
To run the Fixmbr command, enter in the command line of the Management Console:
Fixmbr
Where - the distinguished name of the disk for which you want to create a new master boot record. For example, the distinguished name for the C master boot drive would be:
\ Device \ HardDisk0
Canceling automatic reboot
When a critical error occurs while using Windows XP, the system automatically reboots. If a crash occurs during the Windows XP startup process, the system gets stuck in an endless reboot loop. In this case, turn off the option to automatically restart on system failure.
When the system starts to boot and you see the message “Please select the operating system to start” or hear a single beep, press the key to launch the Windows Advanced Options menu. Then select Disable The Automatic Restart On System Failure and click. From now on, Windows XP will display an error message during the boot process, from which it will be possible to find out the cause of the malfunction.
Restoring from a backup
If you still can't get Windows XP to boot, you can try restoring the system from a backup (if available). The recovery algorithm depends on the backup utility used, which will provide all the necessary instructions.
In-place upgrade
If you can't get Windows XP to boot and there is no backup, you can perform an in-place upgrade. This operation is a reinstallation of the operating system in the same folder (as in the case of updating the version of Windows to a later version) and can fix almost all Windows boot problems.
Insert the Windows XP bootable CD into the drive and restart your computer. When the preparatory phase is complete, the Windows XP setup screen (shown earlier in Figure A) appears. Click to start the installation procedure. After a couple of moments, a page with a license agreement will appear, click to confirm agreement with the terms. Then the program will search for previously installed versions of Windows XP, and after it finds one of them, the second Windows XP installation screen will open (Fig. C).
Rice. C
To restore the selected version, press R, and to install a new copy of Windows XP -. In this case, the operation to repair the corrupted version is identical to an in-place upgrade, so press R. The installer will then check the hard drives for faults and then perform an in-place upgrade.
Please note that after an in-place upgrade or repairing a damaged installation, you will have to reinstall all Windows updates.
| Materials (edit) |
I thought of writing an article on restoration booting Windows XP... In practice, I often met with a situation where Windows simply does not boot, and the "reinstallation again" comes to mind. But sometimes it becomes necessary to simply restore the system without reinstalling. And this, I can tell you, is possible. In 80% of cases, the system can be restored without reinstalling Windows.
I will write a lot, therefore, right off the bat!
First, get yourself a LiveCD or LiveDVD. You can download it here: LiveCD. Also, LiveCD is available in some builds of programs, for example, in ZverDVD. Be sure to burn such a disc. Record on DVD-R or CD-R, as they make deeper and higher quality tracks. Never use RW discs. You will have problems with them.
Now let's look at the essence of the problem. We are considering the issue of no boot Windows XP... That is, the computer turned on, the disks were initialized, but Windows boot Did not happen. The options are described below.
The computer goes into reboot
This means that for Windows failed to boot, and in the boot settings it is written that in case of a failure, the computer needs to be restarted. In order to understand where the failure is, you need to disable the automatic restart of the computer in case of failures. This is done as follows.
While the system boots, hold down the F8 key. The method selection menu will open Windows boot... We select the item "Disable automatic restart on system failure".
The "blue screen of death" opens
Blue Screen of Death is also called BSOD. Its purpose is to show the user what has happened to the system.
The picture shows three pieces of BSOD text that matter to us. Perhaps some of the points may be missing. So what do these points mean:
- 1. The name of the file that caused the system to crash.
- 2. Description of the error.
- 3. Stop code. It can be used to find a solution on the Internet.
Your task is to study this data and find a solution. Alternatively, you can replace the faulty file with a file from the distribution kit. The second option is to boot from the LiveCD, download CureIt and scan the file for viruses.
Computer locked
Sometimes it happens that computer won't boot, and on the screen there is a white inscription on a black background that the computer is locked for one reason or another. It looks like this:
Whatever is written on the screen, the main task is not to send SMS, not pay bills and not spend money on this beggar. We just boot from the LiveCD and scan the disk with the system for viruses. CureIt is ideal for scanning. Usually, after disinfecting the system, the computer boots up quietly.
White cursor on black screen
If a white cursor blinks on a black background while the computer is loading, but the boot does not occur, then the reason is in one of the drivers or a program that hangs in the startup.
In order to understand which file failed, you need to enable the display of running processes at boot time in the system. This is how it is done.
Loading from LiveCD. Open the disk with the system in TotalCommander, and find a file called "boot.ini" in the root. We open it with a notepad. Find a line like this: " multi (0) disk (0) rdisk (0) partition (1) \ WINDOWS = "Microsoft Windows XP Professional RU" / execute / fastdetect". It is necessary to enter the parameter" / sos". The result should look something like this:" multi (0) disk (0) rdisk (0) partition (1) \ WINDOWS = "Microsoft Windows XP Professional RU" / execute / fastdetect / sos". Save the file and reboot. Now, when you boot the system, you will see what is loading. If loading a file takes a long time, then this file crashes. The solution is to replace the file or update the required driver. It may make sense to run the files through antivirus.
Outcome
I have described the most common mistakes and their solutions, if Windows XP won't boot... But each case requires its own solution, so you will need to turn on the brain.
Scanning the system disk with an antivirus program almost always helps. My recommendation is CureIt.
That's all. Good luck in your achievements!
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