What causes a computer to restart on its own or freeze up?
Freeze ups could be caused by malware (malicious software: viruses, etc.) or if you're trying to run a game or any other program that's too much for the system to handle or something. Malware could also probably cause restarts, or if your processor is overheating, that could cause it too (the system would shut down to prevent damage from heat).
As far as hardware is concerned, and depending on your BIOS settings, random restarts can be caused by a bad or failing power supply, bad or mismatched RAM, an overheating cpu, or a faulty peripheral causing windows errors.
As far as software... lots of crap.
The psu ia a new antec, all temps are good. All I did was take the mpbp out and put in new case. I did a raw format and reinstalled windows xp with all the updates. This only happens from time to time and I don't have any games on it. It does not seem to be overloaded. ??
Does it ever give a blue screen (BSOD) before restarting? It sounds like it could be an overheating CPU or something, that it would shut down to prevent damage from heat. Is it whenever you do something that would require pretty much CPU power, or does it happen when idle?
No blue screen, The temps are fine, It does it when it feels like it while i'm working and during screen saver