Left 4 dead 2 stops working when taking control of character.

[Santino]

Hello, I just got left 4 dead 2 like 10 minuets ago. It is my first steam game (besides TF2 witch i have been playing for years) and when I try to do single player it does the intro, zooms in on my characters head, and the when i move the mouse to look around and try to move, it crashes. It said "left 4 dead 2.exe has stopped working" Please help me this is seriously leaving a bad taste in my mouth about this game and steam all together.

I have defragged files and validated files. nothing works. The game runs fine at the main menu, its only until i try to play.

I know that there is probably a better place to post this i just don't know where.
If you want me to post my computer specs I can.