I was playing the first challenge map against the undead on my PS3. Everything was going fine when spontaniously the ranger's arrows stopped working against non-green skeletons with the swords and shields. The arrows still worked against spiders, trolls, archers, zombies and green glowing skeletons with weapons. Not sure why this started up, so much was happening it hard to pin down what I was doing just before this happened. I belive it was the 4th or 5th wave when the issue started. So far I have not had this problem anywhere else.