Bad Pool Caller??

[brentw]

This problem is driving me nuts. Say if I visit youtube and stream a video. If I hit BACK on my browser my computer will restart. Does not always do this, just sometimes. If I'm chatting on Trillian, for some reason it will restart. Right now I cant send a message without it restarting. I tried swapping ram, didnt help. Tried swapping network cards, didn't help. I'm guessing its a software related problem. Any suggestions? I've reformatted several times over the past half a year, the problem still persists.