whoa wtf >_<
the orginal, wont boot!!!
k, you've tried deleting the cache, and all saves?
and tried starting a new game from scratch?
..wow... just crazy. only thing, i can think of my self, is you applyed the patch, which disables the save protection on DOAXVB. then you played longer then 2mins, and maybe used a hacked gamesave. now u removed the protection patch, and now the game will automatically lock just when ever you press on any character icons.
its a long shot, but try downloading xbox-saves.com's gave save manager to check that all the doaxvb saves are gone.
if this doesn't work i got no clue
...and i doubt its a bios problem, or a simular problem with your modded xbox. since it worked before. though the issue, sounds like theres a problem with a new file, present on your xbox now, that was placed there recently.
well my 2cents, good luck