Win XP Pro SP2 rebooting upon startup. HELP!!!!

[chssvl]

This morning I turned off my desktop without any problems. It had been working perfectly.

However, when I came back from work I turned it on and during the "windows xp" loading screen it rebooted itself. Tried again and same thing. Went to safe mode and the same thing happened.

So I took my CD and I repaired the installation (the repair that reinstalls windows). The installation went fine but upon first boot up it rebooted itself again and this time even before the win XP loading screen showed up.

What can I do??? Help!!!!

 

[pscowboy]

Reboot and press F8 after the POST beep. On this menu choose:

"Disable automatic restart on system failure". When your unit finally comes to a stop, there will be an error message. Share that with us.

 

[chssvl]

I had to reinstall everything all over again although I didn't format the windows partition as I had some info there that I couldn't erase.

But now the problems persist. Everything seems to be working fine again after I reinstalled but now I can't install Norton Antivirus. I get a "error installing" message. I'm starting to wonder if perhaps I have virus problems.