Which Version did you buy?
Are you playing with the Original DVD in the Drive?
Did you mod the game in any way?
When posting a problem, please, include the following information about your computer:
• Operating system (if you have XP, Vista, or Win7 and which Service Pack(s) is installed)
• Video Graphics card type?
• How much graphics memory, and is it Dedicated or Shared?
• RAM (random access memory)?
This information may also help to identify your problem.