I believe certain actions in the lobby prior to starting a match can lead to a freeze up, causing the system to lock up completly and when this happens, the BO2 game save becomes corrupt.
One cause is entering "create a class" but barracks and challenges may trigger it also and Domination maps seem especially prone. I can almost always re-create the problem too. What's curious is that Activision doesn't seem to be interested or at least hasn't responded to my efforts to contact them.
It goes like this: If after a lock up and re-boot, I delete the game save file from the game save utility and then go directly into "find a game", I can play without any problems - even Domination and pretty much one game after another BUT it seems if I divert to something like "create a class" while in the lobby or even if I exit the lobby, my next attempt to play will freeze.
It's always happens the same too. In lobby; countdown ends and screen changes. Name of game and location comes up in top left corner of screen but instead of the map graphic coming up next, it stays blank except for the meter bar at the bottom, which continues to move; very soon though, the music stops followed by the screen freeze. If on the other hand, the map graphic DOES appear, the game will load fine and I can play.
I never had any freeze up issues prior to patch 1.06 but since then I've had the above situation 80-90% of the time UNLESS I delete the game save file. This seems to be the only work around I can find.
I tried removing a lot from the HDD but that didn't make any difference. I think this is a software issue and possibly a result of the last patch.