Well I opened the case up today and found the fan on the ATI card is seized up. I'm guessing that what is happening is that when I run a game the chip heats up and fails. The card has a substantial heat sink in addition to the fan, which is why it probably works okay when I'm working in Windows vs. running a 3D game.

What is the possibility of replacing the headsink/fan assembly on this card? Has anyone done it and can provide details or recommend parts?