xp will not start in safe or normal mode

Or this

How to Recover from a Corrupted Registry that Prevents Windows XP from Starting
http://support.microsoft.com/search/preview.aspx?scid=kb;en-us;307545

BEGIN ARTICLE

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The information in this article applies to:

Microsoft Windows XP Home Edition
Microsoft Windows XP Professional
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SUMMARY
This article describes how to recover a Windows XP system that does not start because of corruption in the registry. This procedure does not guarantee full recovery of the system to a previous state; however, you should be able to recover data when you use this procedure.

You can repair a corrupted registry in Windows XP. Corrupted registry files can cause a variety of different error messages. Please refer to the Knowledge Base for articles regarding error messages related to registry issues.

This article assumes that normal recovery methods have failed and access to the system is not available except by using Recovery Console. If an Automatic System Recovery (ASR) backup exists, it is the preferred method for recovery; it is recommended that you use the ASR backup before you try the procedure described in this article.


MORE INFORMATION
When you try to start or restart your Windows XP-based computer, you may receive one of the following error messages:

Windows XP could not start because the following file is missing or corrupt: \WINDOWS\SYSTEM32\CONFIG\SYSTEM
Windows XP could not start because the following file is missing or corrupt: \WINDOWS\SYSTEM32\CONFIG\SOFTWARE
Stop: c0000218 {Registry File Failure} The registry cannot load the hive (file): \SystemRoot\System32\Config\SOFTWARE or its log or alternate
The procedure described in this article uses Recovery Console, System Restore, and lists all the required steps in specific order to ensure that the process completes fully. After you complete this procedure, the system should return to a state very close to the system before the problem occurred. If you have ever run NTBackup and completed a system state backup, you do not have to follow the procedures in parts two and three; you can skip to part four.
Part One
In part one, you boot to the Recovery Console, create a temporary folder, back up the existing registry files to a new location, delete the registry files at their existing location, and then copy the registry files from the repair folder to the System32\Config folder. When you are finished this procedure, a registry is created that you can use to boot back into Windows XP. This registry was created and saved during the initial setup of Windows XP, so any changes and settings that took place after Setup completes are lost.

To complete part one, follow these steps:
Boot to the Recovery Console.

At the Recovery Console command prompt, type the following lines, pressing ENTER after you type each line:

md tmp
copy c:\windows\system32\config\system c:\windows\tmp\system.bak
copy c:\windows\system32\config\software c:\windows\tmp\software.bak
copy c:\windows\system32\config\sam c:\windows\tmp\sam.bak
copy c:\windows\system32\config\security c:\windows\tmp\security.bak
copy c:\windows\system32\config\default c:\windows\tmp\default.bak

delete c:\windows\system32\config\system
delete c:\windows\system32\config\software
delete c:\windows\system32\config\sam
delete c:\windows\system32\config\security
delete c:\windows\system32\config\default

copy c:\windows\repair\system c:\windows\system32\config\system
copy c:\windows\repair\software c:\windows\system32\config\software
copy c:\windows\repair\sam c:\windows\system32\config\sam
copy c:\windows\repair\security c:\windows\system32\config\security
copy c:\windows\repair\default c:\windows\system32\config\default

NOTE : This procedure assumes that Windows XP is installed to the C:\Windows folder. Make sure to change C:\Windows to the appropriate windows_folder if it is a different location.

If you have access to another computer, to save time, you can copy the text in step two, and then create a text file called "Regcopy1.txt" (for example). To create this file, run the following command when you boot into Recovery Console:
batch regcopy1.txt
The Batch command in Recovery Console allows for all the commands in a text file to be sequentially processed. When you use the batch command, you do not have to manually type as many commands.
Part Two
In part two, you copy the registry files from their backed up location by using System Restore. This folder is not available in Recovery Console and is normally not visible during normal usage. Before you start this procedure, you must change several settings to make the folder visible:
Start Windows Explorer.

On the Tools menu, click Folder options .

Click the View tab.

Under Hidden files and folders , click to select Show hidden files and folders , and then click to clear the Hide protected operating system files (Recommended) check box.

Click Yes when the dialog box is displayed that confirms that you want to display these files.

Double-click the drive where you installed Windows XP to get a list of the folders. If is important to click the correct drive.

Open the System Volume Information folder. This folder appears dimmed folder because it is set as a super-hidden folder.

NOTE : This folder contains one or more _restore {GUID} folders such as "_restore{87BD3667-3246-476B-923F-F86E30B3E7F8}".

NOTE: You may receive the following error message:
C:\System Volume Information is not accessible. Access is denied.
If you get this message, see the following Microsoft Knowledge Base article to gain access to this folder and continue with the procedure:

Q309531 How to Gain Access to the System Volume Information Folder
Open a folder that was not created at the current time. You may have to click Details on the View menu to see when these folders were created. There may be one or more folders starting with "RP x under this folder. These are restore points.

Open one of these folders to locate a Snapshot subfolder folder; the following path is an example of a folder path to the Snapshot folder:

C:\System Volume Information\_restore{D86480E3-73EF-47BC-A0EB-A81BE6EE3ED8}\RP1\Snapshot
From the Snapshot folder, copy the following files to the C:\Windows\Tmp folder:

_REGISTRY_USER_.DEFAULT
_REGISTRY_MACHINE_SECURITY
_REGISTRY_MACHINE_SOFTWARE
_REGISTRY_MACHINE_SYSTEM
_REGISTRY_MACHINE_SAM
These files are the backed up registry files from System Restore. Because you used the registry file created by Setup, this registry does not know that these restore points exist and are available. A new folder is created with a new GUID under System Volume Information and a restore point is created that includes a copy of the registry files that were copied during part one. This is why it is important not to use the most current folder, especially if the time stamp on the folder is the same as the current time.

The current system configuration is not aware of the previous restore points. You need a previous copy of the registry from a previous restore point to make the previous restore points available again.

The registry files that were copied to the Tmp folder in the C:\Windows folder are moved to ensure the files are available under Recovery Console. You need to use these files to replace the registry files currently in the C:\Windows\System32\Config folder. Recovery Console has limited folder access and cannot copy files from the System Volume folder by default.

NOTE : The procedure described in this section assumes that you are running your computer with the FAT32 file system.
Part Three
In part three, you delete the existing registry files, and then copy the System Restore Registry files to the C:\Windows\System32\Config folder:
Boot to Recovery Console.

At the Recovery Console command prompt, type the following lines, pressing ENTER after you type each line:
del c:\windows\system32\config\sam

del c:\windows\system32\config\security

del c:\windows\system32\config\software

del c:\windows\system32\config\default

del c:\windows\system32\config\system

copy c:\windows\tmp\_registry_machine_software c:\windows\system32\config\software

copy c:\windows\tmp\_registry_machine_system c:\windows\system32\config\system

copy c:\windows\tmp\_registry_machine_sam c:\windows\system32\config\sam

copy c:\windows\tmp\_registry_machine_security c:\windows\system32\config\security

copy c:\windows\tmp\_registry_user_.default c:\windows\system32\config\default
NOTE : Some of the preceding command lines may be wrapped for readability.

NOTE : This procedure assumes that Windows XP is installed to the C:\Windows folder. Make sure to change C:\Windows to the appropriate windows_folder if it is a different location.

If you have access to another computer, to save time, you can copy the text in step two, and then create a text file called "Regcopy1.txt" (for example).
Part Four
Click Start , and then click All Programs .

Click Accessories , and then click System Tools .

Click System Restore , and then click Restore to a previous Restore Point .

REFERENCES
For additional information about using Recovery Console, click the article numbers below to view the articles in the Microsoft Knowledge Base:

Q307654 HOW TO: Access the Recovery Console During Startup
Q216417 How to Install the Windows XP Recovery Console
Q240831 How to Copy Files from Recovery Console to Removable Media
Q314058 Description of the Windows XP Recovery Console
For additional information about System Restore, click the article numbers below to view the articles in the Microsoft Knowledge Base:
Q306084 HOW TO: Restore Windows XP to a Previous State
Q261716 System Restore Removes Files During a Restore Procedure

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Published Oct 24 2001 9:05AM  Issue Type kbinfo  
Last Modifed Mar 22 2002 4:49PM  Additional Query Words  
Keywords kbenv

COPYRIGHT NOTICE. Copyright 2002 Microsoft Corporation, One Microsoft Way, Redmond, Washington 98052-6399 U.S.A. All rights reserved.
 
END  ARTICLE  


Here is how fellow Expert Axter got his system back to normal

Boot to the Recovery Console.
At the Recovery Console command prompt, type the following lines, pressing ENTER after you type each line:
md tmp_r
copy c:\windows\system32\config\system c:\windows\tmp_r\system.bak
copy c:\windows\system32\config\software c:\windows\tmp_r\software.bak
copy c:\windows\system32\config\sam c:\windows\tmp_r\sam.bak
copy c:\windows\system32\config\security c:\windows\tmp_r\security.bak
copy c:\windows\system32\config\default c:\windows\tmp_r\default.bak

delete c:\windows\system32\config\system
delete c:\windows\system32\config\software
delete c:\windows\system32\config\sam
delete c:\windows\system32\config\security
delete c:\windows\system32\config\default

copy c:\windows\repair\system c:\windows\system32\config\system
copy c:\windows\repair\software c:\windows\system32\config\software
copy c:\windows\repair\sam c:\windows\system32\config\sam
copy c:\windows\repair\security c:\windows\system32\config\security
copy c:\windows\repair\default c:\windows\system32\config\default

Then after that, you can reboot to XP in normal mode.

Once you do a full boot into XP, go to the "C:\System Volume Information" directory.
If you don't see this directory, or don't have access to it, check the following link for some instructions on how to access this folder.
http://support.microsoft.com/default.aspx?scid=kb;[LN];Q309531

Look inside this folder you'll see additional folders that have names that look like the following:
_restore{5C4DCC9D-E782-4845-AB2A-E820210EC1E4}

Open the folder with the latest date stamp, or a date stamp that represents the last day&time you think you had a valid registry.
Inside the above folder, you'll find more folders:
RP0
RP1
RP3
etc....

Each one of these folders has a copy of the registry files stored in a subfolder called snapshot.  The folder with the biggist number, is the latest backup.
Select the sub folder you want to use to restore your registry.
Example:

C:\System Volume Information\_restore{5C4DCC9D-E782-4845-AB2A-E820210EC1E4}\RP7\snapshot

Useing your selected folder copy the registry file to a folder that has normal access.
Example:
mkdir c:\windows\good_reg
copy C:\System Volume Information\_restore{5C4DCC9D-E782-4845-AB2A-E820210EC1E4}\RP7\snapshot\_REGISTRY_MACHINE_SYSTEM c:\windows\good_reg\system
copy C:\System Volume Information\_restore{5C4DCC9D-E782-4845-AB2A-E820210EC1E4}\RP7\snapshot\_REGISTRY_MACHINE_SOFTWARE c:\windows\good_reg\software
copy C:\System Volume Information\_restore{5C4DCC9D-E782-4845-AB2A-E820210EC1E4}\RP7\snapshot\_REGISTRY_MACHINE_SAM c:\windows\good_reg\sam
copy C:\System Volume Information\_restore{5C4DCC9D-E782-4845-AB2A-E820210EC1E4}\RP7\snapshot\_REGISTRY_MACHINE_SECURITY c:\windows\good_reg\security
copy C:\System Volume Information\_restore{5C4DCC9D-E782-4845-AB2A-E820210EC1E4}\RP7\snapshot\_REGISTRY_USER_.DEFAULT c:\windows\good_reg\default

Now reboot to the Recovery Console.
At the Recovery Console command prompt, type the following lines, pressing ENTER after you type each line:
copy c:\windows\good_reg\system c:\windows\system32\config\system
copy c:\windows\good_reg\software c:\windows\system32\config\software
copy c:\windows\good_reg\sam c:\windows\system32\config\sam
copy c:\windows\good_reg\security c:\windows\system32\config\security
copy c:\windows\good_reg\default c:\windows\system32\config\default