In phase1 KT when the mobs are coming out of their alcoves into the center, if a hunter multi-shots some skeletons who are still in their alcove and immediately feign-deaths, the entire encounter will despawn for about 15 seconds. When it starts back up, it will be reset. I would guess this is a side effect of the strange nature of the aggro on KT skeletons.
This could be used for fun, or maybe as revenge for a terrible pug.6):
Also, there will not be any screenshots as I don't plan on going to Naxx25 anytime soon but it should be easy enough to understand without them.