Did you try running with stock settings to eliminate any software/OS issues? I had this problem with my setup as well. I was able to run gobs and gobs of IBT, OCCT, Prime95 and even MemTest86. But I would lockup during mundane tasks such as surfing the net, idling, etc. Good members in this forum suggested that it was due to the fact I had power savings options on - EIST, Speed spectrum, etc. I turned all those off so my comp is basically at 3.8 Ghz all the time. And no issues. Of course, I started all over from scratch - meaning I discarded my previous overclock values and overclocked one more time to 3.8 ensuring I took my time and did it right.
I also took my Phsyx card out.
Edited by Tennobanzai - 2/1/11 at 11:51am