Windows XP Keeps Restarting Problem (Solved)

How to Fix a Windows XP Reboot Loop

Start the computer from the Windows XP CD-ROM.

At the "Welcome to Setup" screen, press R to repair a Windows XP 

installation by using the Recovery Console.

Type the number that corresponds to the Windows installation that you 

want to repair, and then press ENTER. For example, type "1" (without the 

quotation marks), and then press Enter.

When you are prompted for a password, type the local Administrator 

password, and then press ENTER. (If you are not prompted for a password, skip 

to the next step.)

Step 1. Inside “Recovery Console” text dialog, type: “chkdsk /P” without the quotes. A process checking your system drive for bad sectors and corrupted files will follow. This is critical to finish, to the use of the next 3 commands that will fix your problem.

Step 2. Use “bootcfg /rebuild” command, without the quotes to rebuild your boot.ini. In here, you might be asked for a few additional details, like identifying the operating system and confirming it with Y for “yes”. (Optional)

Step 3. Use “fixboot” command, without the quotes. This is optional but I would do it if I were you, just in case step 2 didn’t work as planned.

Step 4. Use “fixmbr”command, without the quotes.

Type "cd system32" (without the quotation marks), and then press ENTER.

Type "cd config" (without the quotation marks), and then press ENTER.

The command prompt will be similar to the following (where <Windows> is 

the folder in which Windows is installed):

C:\<Windows>\System32\Config>

Type "rename system system.old" (without the quotation marks), and then 

press ENTER.

Type "copy c:\windows\repair\system" (without the quotation marks), and 

then press ENTER.

Type "cd system32" at the command prompt and press "Enter."

Type "ren kernel32.dll kernel32.old" to rename the existing kernel file and press the "Enter" key.

Type the word "map" and press "Enter." Enter the drive letter of the CD-ROM.

Type "expand drive\i386\kernel32.dl_" and press "Enter." This command expands the kernel file from the CD-ROM. When the process completes, type "Exit" at the command prompt to restart the computer.

Type "cd system32" without quotes when the command prompt appears. Press "Enter," type "ren kernel32.dll kernel32.old" and press "Enter" again. Type "map" and press "Enter."

Type "expand d:\\i386\\kernel32.dl_" and press "Enter." If the Windows XP CD is inserted into a drive other than "D:" replace "D:" with the proper drive letter.

Type "exit" and press the "Enter" key. The computer will shut down and reboot again. Remove the Windows XP disk. The reboot loop should now be resolved.

References:

http://www.ehow.com/how_5004158_fix-windows-xp-reboot-loop.html

http://techchannel.radioshack.com/fix-windows-xp-reboot-loop-1846.html