First off, please try to verify the game cache through the steam client. For information on how to do this, please see: Verify Game Cache Files (GCF) - How To's - Knowledge Base - Steam Support
Also, have you taken a look at our knowledge base article regarding computer performance issues: Activision Support
Th3_Doctor was about to say the same thing, but saw the tags
Ok it has sort of worked but not fully...
Multiplayer will load, get in game and wont load fast so it doesnt get into the game. Singleplayer on the otherhand starts up the starting video in a flash but still freezes.
Thanks for the help so far but I still need more help.