A little advice from a computer nerd/freak/gamer:
Look at sign. "Kruger:" lower part of the screen and all the icons there, see them?
Those are also called "CPU-vampires", the cleaner that section is, the more likely it will be that there will be no mess up with games etc,etc, because these are little tiny "vampires"/programs that are probably running in the background for no good when you play a game. Keep that section clean.
Go to Start/Run and write msconfig ( or in Vista just search on the word msconfig) and look in services in there, i.e. disable Microsoft Services to see what is running beside MS services, and I for example, I have only "Nvidia display" drivers running and also look in Startup,,keep that section clean too and your gaming experience will be more "bump-free"/lock-ups free/slowdown free and so on,,besides that:
WHERE the heck did you get the game!!!!!!!! 