My xbox freezes after the Ceph mastermind boss fight at the loading screen after the cement falls on you and then I have to do the boss fight all over again

You are not alone with this (i hang like others, on Alpha) - http://secure.gamesas.com/forums/viewtopic.php?f=68&t=59449&p=607748#p607748

It only happened twice but still that's not going to be fun when I'm doing my supersoldier playthrough