I've implemented a quick stop-gap solution to traderoom problems. Now, there's no real way for a card to get 'lost in the ether' during an error at quit. This doesn't SOLVE the error (I still haven't seen it myself) and it'll probably slow trading down a little more, but now every time you move a card it moves it into an actual physical (instead of temporary) deck and these decks are what are traded. The worst case is that somehow two people end up with the same deck, but this should be negligably rare.