Atikmdag crash only in Fallout 3

[D_V_A]

I have Windows 7 and ATI Radeon Graphics card

I have tons of games in my pc, you see? how come 5 minutes or less into Fallout 3 my display driver crashes? it used to be rarely, but now it's less than 5 minutes in :( immediate crash to desktop and the stupid Display Driver Stopped Responding and Has Recovered warning :(

http://img241.imageshack.us/img241/8366/atimkdag.jpg

(not my image but very well could be)

 

I can't remember the last time I've clicked the "Quit Game" in the FO3 menu

 

 

what you should know:

I tried the basic windows theme (not Aero) and it still crashed

I don't overclock anything.

my ATI driver is up to date, I've reinstalled it numerous times.

no other game does this (well maybe Blur and Mass Effect 2 also crash without a reason, but the display driver warning doesn't appear in the corner there)

for example I've played Dark Void for 6 hours straight last night and quit the game from its menu :P Other games like Fuel, Assassin's Creed 2, Batman: Arkham Asylum, Rainbow Six Vegas 2, Modern Warfare 2 and many others work without a single crash

 

I'm just... stuck on what to do :(

any suggestions?