In the American version of the game only, if you play as Alyssa and Ad-lib,
there is a good chance that the game will freeze, causing you to lose any
unsaved game data, and have to reset the PS2. This isn't a problem as long as
you either don't play as Alyssa, or play as Alyssa but don't Ad-lib.
It is quite possible that, when playing Outbreak, if you leave Main Street and
your friends activate the detonator, you could be stuck. I discovered this
myself, and I was just about to get a NO WEAPON CLEAR/NO DAMAGE CLEAR combo.
You can run back to the car, but you can't talk to Officer Dorian, and the
stairs turn into an endless staircase. Watch out!