I stopped using mintpal since I once saw something really strange. I had an open sell order, and I saw some one bought my sell order and some of the sell orders above me. And this all was visible in the transaction history, where you can see the buys & sells that people made. Then suddenly everything changed, my sell order and other sell orders that were bought by some one now again appeared as open sell order section, like nothing has happened. This is very weird, my coins were sold, I had the BTC in my balance, then my BTC balance was gone, and I had my coins back.