OK, I've noticed a pattern with the One-player quests that is really pissing me off; and I mean SERIOUSLY!!!
When you go into one-player mode, and do one of the main story quests (aka the offline quests like Soul of a Blacksmith, or Doc Octo's Research etc etc) and you get done with the quest, and are ready to go turn it in, if you go to your common bank BEFORE turning in the quest - it acts like you selected QUIT GAME and YES from the menu even though the menu isn't open . . . . this has happened to me several times now, and frankly, IT'S EFFIN RIDICULOUS!
I had to do Unsealed Door 4 EFFIN TIMES before the game didn't crash!!!!
I always deposit stuff in the bank before turning in a quest, that way I can start the next quest fresh - FIX THIS, BECAUSE THIS IS ANNOYING AS F*&&^k