90% SVGA card or SVGA chip problem.
5% XP crashed.
5% MainBoard fail.
1. Try unplug the SVGA card and clean the gold fingers by using rubber.
2. Also test the SVGA chip fan, clean the fan also.
If still cannot fix, try to look at the MainBoard to see if any components brust, such as capaitor.
If fail components were found, need replace MainBoard!
If no fail component, you may need to re-install XP to fix the problem.
Before re-install XP, try download the IDESCAN.exe to check the HDD. To see if your XP crashed because of HDD failure.
Search the IDESCAN from yahoo and download the IDESCAN.exe version 1.0 to a boot disk.
Boot up your PC and test the HDD.