After a wipe on Four Horsemen, a hunter had feigned death in our raid in order to try and survive a wipe. He successfully caused the bosses to reset, however when he went out of Feign Death and subsequently died it caused the doors of The Four Horsemen to stay locked even though there was nobody in the room. This prevented us from being able to kill Four Horsemen and complete Naxx as we had no way to get inside the room.