I had a similar problem.  Same lockup during loading screen - it just goes black and the Xbox stops responding completely.  After the Jan update, instead of a total unresponsive Xbox black screen, I get a message that the hard drive is no longer attached to the Xbox.

Lionhead and Microsoft showed their f!@#$% asses on this game.  There are so many crashing issues.  I have no invested interest to start a new game - because this is just going to happen again.  When I emailed Lionhead about the issue they just referred me to their update page and said that something is being done about a fix to some of the problems out there. 

I guess ours was not addressed.

Wolf-