Just have been playing LFS, and my monitor blanked out, the GPU fan started spinning at maximum speed, and I could not reset it, I had to unplug the PC from the socket...first time that happened.

After I managed to restart the PC I checked the GPU and CPU temps...all normal. Tried playing LFS, rfactor, portal - did not happen again so far.
PC specs: Athlon X2 64 6000+, ATi 3850, ASRock AM2XLi-Esata2 mobo, corsair VX450 power supply, Win XP SP3, all patched, all latest drivers, no viruses or other shit.

Quote from Thunderhead :

ATi 3850 ... all latest drivers

I've had an issue with LFS on Cat 9.2 drivers a couple of times lately too. Rather than my monitor going blank LFS hangs and can't be closed using Task Manager or Process Explorer. I need to reboot the PC to actually close it. The PC itself doesn't hang, but it could be something similar to your problem.

I'm using Vista Home Premium 32 bit, 9.2 Cats and an HD3870x2.

downgraded catalysts to 8.10-only version I had and dont remember having problems so far...(and I had that one before upgrading to 9.2) same thing.

My ATI card does this from time to time, i eventually get an error message that goes something like ' Your graphics hardware stopped responding to commands and all settings were restored to default'

I just messed about with aa/af settings and it went away.