from their home page

Earlier today while adding a new pool on our European machine, we accidentally configured our cronjobs incorrectly. What this means is that the process which queries the database for payments and then sends them out accordingly was accidentally run twice, causing payments to be double sent and our server wallet to be emptied. All of our users without autopayments set up (and many with it) lost their entire coin balance stored on the server. We know what caused the issue and it was entirely our fault. Nothing was hacked. We have taken steps to ensure this never happens again. Everything is now running smoothly and will continue to do so.

Sincere apologies, ~The HSG Team