On PS3: Game drops from multiplayer to loading and then crashes...

Starting the day before yesterday I started experiencing an issue where, after a few minutes, the game will drop from any multiplayer session (including Test Range) and the black "loading" screen will appear, and a few seconds later the whole game just crashes and the PS3 Home Screen comes back up...

This is very frustrating - and confusing! There wasn't even a patch or upgrade - why is this suddenly happening and how can I fix my game!??!?

Thanks