I was in the middle of a battle in the colosseum, and I clicked another tab to check up on something... When I returned, the game had reset itself saying it doesn't allow multi-instances... -_-
I understand you have to program these anti-cheating catches into the game, and that it might be a nightmare to have to suss out every possible loophole and patch them all--but perhaps it's not a good idea to knock a player's bonus all the way back to zero... at least not until you can guarantee this won't happen again.