Game freezes up in zombies call of duty black ops Xbox 360 in teleport room?

When I play call of duty black ops zombies, my game always freezes up in the same place:
When I teleport up into the projection room.
I don’t have xbox live, and i saved the game to the hard drive. I’m going to go to gamestop tomorrow to let them clean the disk, but does anyone know whats going on? I mean, I have ray gun, or thunder gun, and start throwing grenades down there, and it just freezes. Can anyone help?

Damn Technology, it’s a bug or a freeze, probably an issue with the game ,I hope Gamestop figures it out. Good luck!