There have been a few posts in this thread from ATI users as well, however it could be a different cause. The majority seem to be nvidia users with newer series cards.

That being said: yesterday I did a system restore to 4 days before my issues started and so far I have not had any problems. The only changes that were reversed by the system restore were 3 Windows updates and an uninstall of my G930 Logitech headset drivers. I was able to play last night for 3 hours without issue. Usually I can only play maybe 15 minutes. This leads me to believe that either a) a Windows update caused this problem or b) something I did within the game itself corrupted a system or game file, causing the game to crash every subsequent time I tried to play. I am leaning towards option B since the first time it happened, I was playing for about 3 hours, finished Haukke HM and as soon as the cutscene started, the computer shut off.

Sigh, but still.. so many theories but no concrete answers or solutions yet. I am sceptical that my system restore is a permanently solution. If I can get it to happen again, I will report back.