I rememeber reading a game informer article about goofiest video game bugs and one was from oblivion in which the player would go find a character in jail only for that character to be dead for some reason breaking the quest. They couldn't figure out why he died until by chance, a tester saw a guard walk over to the cell, kill the NPC, take food off his body and eat it. Apparently the guard's routine required him to eat food so he resorted to killing the NPC to get it. The programmers fixed it by giving the guard more food in his inventory