Well i searched every possible forum now and did not really get an answer.. some ppl also told me i need a new grafik card... sure...
Anyway...
I worked it out (and strange i had this problem once b4) as followed:
I deleted the HDD content of the game via Steam (right click on it and delete game)
and afterwards installed it without the disc, just only via steam.
Restart afterwards... and see.. now it runs...
Dont ask me why... i really got no idea... it was the same for me with Metro 2033.
Both games installed a driver after installing from CD and never really worked then.
After installing from steam without a cd they work fine.
Anyhow... maybe you wanna try this way...