I have a purpose-built desktop running Windows 7 Home Premium.
Radeon 6870 card, Intel HD Graphics on MB, i2500K CPU, 8 GB RAM, Gigabyte Mother board, 850W Power supply.
I am having the same problem but it is only occurring (so far) on Second Life. I have recently upgraded my ATi driver and I suspect that is where the problem is since it only started after that.
Ran HWMonitor and the only things that seemed out of line was that my -5v was measured at -6 v and the +5 v was at 2.82v and the temperature n my solid state memeory (OCZ) was 262 F. (But who knows what the temp SHOULD be). By the way the temp of the Radeon
card was 112 F and the voltage was 0.95v, but again what should they be?
I have just tried "rolling back" my display driver and will see if that has any effect.
So far it seems to be working.