Game & PC freeze while Intro

[Datenpapst]

I am using a Alienware m9700 Aurora Notebook with 2 GB DDR Ram, 2,0 GHz, and 2x 256 MB DDR SLi nVIDIA 7900 GS

When I start the Game it asks me to log into the LiveAccount, I press ESC the Game launches, loads the SaveGame (have never played), and starts the Intro, sometimes it takes 10-20 Secs but finally the Game and the whole PC freeze and I have to press the Power-Button. What the hell happens here?