Dammit, my NAV has been frozen on Poloniex for almost a month and I can't do anything with it.
Please fix the wallet for them! The admins tell me I can't get it back until the wallet is fixed.
Can someone explain to me why Bittrex doesn't seem to have the problems that poloniex and cryptsy have?

Polo tried to resync the wallet, Bittrex did not, I think. But I also read in this thread the fix is in process. Just wait a bit till SUM2Dev announces the patched wallet.