Every time i try to get into a server the game swtiches to the loading screen but it says "invalid cd key" and the game just sits and sits. I know i put the right code in b/c the single player works fine...any suggestion?????

Many people can use the same code for single player... But only 1 for multiplayer.. If you actually bought the game then you should contact the manufacture about this.. If you got a copy then you will need a patch to play multiplayer or to buy the game.