Well I'm glad it is fixed for now... Also, though I don't play COD4 much, I hope you got your lag\crashing issues fixed there...
I had a similar problen where my MOBO had a socket problem from all the moving I do, in which bumping the case, or even the fans could shake the CPU and then the PSU immediately cuts power...
I once had a problem where my PSU was the culprit to this exact problem, but after a few months it made itself pretty obvious, when the PSU actually arced inside of my case during a CAL match and fried 5 resistors and melted the casing on the 5W Power resistors and overcurrent prevention circuit... I suppose that's what you get from a PSU that comes with a case.... A chinese case at that
