I think I've got a bugged copy of the game- just after leaving the Vault the game becomes remarkably erratic- every step I take it's like my character's about to fall through the floor, he can't jump, enemies appear and disappear at random and some background items seem to be levitating like Indian fakirs. Anyone else experiencing this or is it just me? (Yes, I have reloaded the save, and tried an older one, same problem).