If you have updated your computer to have windows xp service pack 2 (SP2)
then while your computer is first powering on tap f8 continuously. In the
list you should see an option that says disable automatic reboot after
failure, move to it with your pointer and click enter. Now you should get a
blue screen stating an error message.
If you don't have service pack 2 then you may also try hitting the f8 and
choosing safe mode. If your computer can boot into safemode without
restarting you can go to start > control panel > performance and maintanence
system > advanced tab > Settings under startup and recovery > uncheck
automatically restart under system failure > ok > ok > restart. You should
now get the blue screen with the error message. You can repost what the
error message is on here and we can help you out some more.
If neither step works then you may need to run a repair install if so post
back and we'll help you with that. Good Luck.
Joe
Kemco IT Professional