They locked my account with no warning 4 days ago: Imgur
They gave me a 'hard to believe story' 3 days ago and then disappeared: Imgur
Add to this that I've written to them multiple times telling them that I've got open margin positions and I risk losing a significant amount if a currency swings in a wrong direction because I have lost control.
This could a sign that something may not be right at Poloniex. I'm very worried.