My computer keeps freezing!!!

[LuckyTaxi]

I have a chaintech (i forget the model number) with a sempron cpu. It has 1GB of ram and was running just fine for the past two months on freebsd. I converted it to a workstation and installed windows xp. It randomly freezes, hence I would need to reboot the computer. I swapped out memory and that's not it. I really dont want to reinstall windows xp, but I dont think it is windows. I see no error messages in the event viewer, nor was I presented with one.