I have triggered this ~50% of the time I play a specific Aether/Fire deck. The basis of the deck is to stall and stockpile fire quanta, and then use a flurry of firebolts to kill the opponent in 1 turn. This deck is one I grabbed from the unupped FG killer decks posted on the forums. Rather than post the entire deck code here is a link (
http://elementscommunity.org/forum/index.php/topic,11024.0.html) to the thread. The deck in question is the second one down created by twinsbuster titled "Fire Lance sudden killer".
The trigger appears to be the fire bolts. When I play them it will desync the game and instead of producing the victory instead I lose control and the computer takes over with my opponent having generally around 20-30 life remaining.
There is also a secondary trigger I have not been able to determine yet as roughly 10-20% of the desync's will occur 1 or 2 turns before I intend to use the fire bolts. I suspect this may be related to the length of the game since it always occurs on turn 25 or later. All my other decks are speed rush decks and I have never encountered a desync issue on them and those games rarely last even 10 turns.
I will attempt to recreate this today a few times if possible and post the screenshots in this post.