If you can't launch the game we very much suggest reading our Steam FAQ first of all, the first port of call is normally to verify the steam cache - http://community.sigames.com/showthr...*OFFICIAL*-FAQ

If you're running BitDefender and are having issues please read the following - http://community.sigames.com/showthr...=1#post7155661

If you've tried the advice in here with no luck, can you please create your OWN thread (even if someone has exactly the same issue), state exactly what your problem is and post your dxdiag.

How do I find my dxdiag?

1. Go to your Start Menu (Windows).
2. XP: Click on Run in the Start Menu. Vista: On the bottom left there should be start search area. Type in Run then press Enter.
3. Type in dxdiag then press Enter.
4. Dxdiag window should open. If it asks you all sorts of license questions just say yes..
5. On the bottom portion of the dxdiag window there should be a button that says Save All or something like that.
6. Save the file as a txt document.

We'll try to get to your issue as soon as we can. Thanks.