I always tell people to be cautious with exchanges. Cryptsy has been mentioned to be controversial to say the least, but in all honesty I have never lost any coins there. They are however extremely slow with withdrawals and indeed seem cut them in half all the time.

My advise would be to never have more than the equivalent of 1-2 BTC on it at all times and withdraw to cold storage frequently.

I'm currently waiting over 12 hours already on a 2.6 BTC withdrawal...