Thats happening for my guild on heroic lich king. Noob pallies don't know how to time heals in that brief .26 seconds they have before the tank randomly goes from 100% to dead. And on one occasion one of them managed to get a LoH's off, but the game was like "LoL I don't care your dead anyways". Recount showed the tank at 40% hp, the LoH criting for 60k overheal (no healing actually done) then dieing .1 second later