"The Storm" Mission On Halo 3 Help!

I've already posted in the lounge section but it seems like nobody cares.. I'm playing Halo 3 on Xbox 360 and i got to this mission called "The Storm". While i was waiting for it load, i realized it keeps going to %20 and come back down %0. It did that 3 times and after that it says "Players failed to load content". Is it the disc or something else ?