COD4 iw3mp.exe stopped working at launch

Hi everyone, I have had COD4 for a while now but I can't seem to open my multiplayer sucessfully. Everytime I open multiplayer I get a message saying "iw3mp.exe has stopped working". I have read and watched many instructions on how to fix this problem, all of which saying to fix the stereo mix and stuff like that but the thing is, I don't have any audio devices installed on my computer and I don't know any other ways of fixing this problem without reinstalling it. Can anybody give me some instructions as to how to fix this problem?

Thanks a lot