I don't believe this is related to my video card overheating. I've played Doom 3, FEAR Demo, Thief 3, HL2, Far Cry with no problems at all. Only when I play Civ IV. Here's my specs:
3GHz P4
1 GB RAM
Radeon 9800 Pro (updated to latest drivers yesterday, no difference)
Audigy 2 ZS Sound Card...