The new forums will be named Coin Return (based on the most recent vote)! You can check on the status and timeline of the transition to the new forums here.
I updated my drivers to the most recent ones, blew the dust out of the card (which helped, I can get more time before the error occurs) and opened the case up.
It seems like a heat issue, but it's only with M:TW 2. WoW runs fine, as did L4D and DoW2 recently.
The card if an nbvidia geforce 7800 GT.
I played Medieval 2 without problems when I first bought it, so this is something new.