I hope it's not another gox! I loaded a bunch of MINT onto Poloniex and sold it during the recent pump. Tried to withdraw BTC to 3 wallets. It froze withdraws, I put in a ticket about 12 hrs ago, no response. Have about 1 1/4 btc stuck. I hope this isn't a snatch and grab or another insolvent exchange. I would recommend caution if you're thinking of depositing there.
That still are only hours, I would not be afraid. Write ticket to support and wait for an answer.
Poloniex had in the past a lot of problems and fixed everything out. This exchange is working for their future.