first of all try a repair of XP
Repair XP by replacing corrupt files
in the run box, press enter and let system file checker find and replace missing / corrupt file in windows and explorer.This will take awhile to complete and you may be asked for the CD to be in the drive if windows is not preinstalled on the hard drive.
sfc /scannow problems
Open System Properties via Start > Control Panel > Performance and Maintenance > System
[ System Properties may also be opened using the WinKey+Pause key combination ]
Select the Advanced tab and then click Settings in the Startup and Recovery section
In System Failure section, clear the checkbox next to Automatically Restart
Click OK and OK to exit
Now you should be able to see the error message when windows crashes.
Post the message here for further help.