Game Freezes Constantly

For whatever reason, my copy of Black Ops seems to freeze constantly. It freezes about three seconds after starting the campaign each time, and it also locks up less than thirty seconds after starting a multiplayer or zombie game. Has anyone else experienced this? It literally happens to me every time. The game is unplayable. I've tried installing it to the hard drive and redownloading the update, along with clearing the cache and stuff like that. Nothing changes. The game doesn't appear to be scratched or anything like that - it just doesn't work on my 360. Other games do, but this doesn't. Has anyone else experienced anything like this? Or does anyone have any suggestions for fixing the problems?

Thanks for any help.