I've been cruising the bugs forums everyday and I've noticed a lot of posts like this:
Arena Game Halt - Light Justice 1st turn Bug - Forums - Hearthstone
Basically, there are a lot of cases where someone plays a weapon card "Truesilver champion, Assassin's blade, etc etc" and it gets stuck midway casting forcing the game to freeze. I've been trying to figure how to reproduce this with no results. Anyone have any ideas or theories?