Same happened to me on MtGox (to make it clear, not their fault, was my own carelessness). Was more than likely related to reuse of password and a hack on another site that used the same acc/pass combination.
There is nothing one can do. MtGox can't protect users from getting their account hacked when it's nothing they've done. I filed a police report, but there's not much the police can do in the case of btc...
One learns from ones mistakes, so, now; stopped reusing passwords, and added two-way auth for important/sensitive things, alas, a bit too late (got 9 btc stolen ;_; although at the time, they were only worth ~100$/btc).
There is nothing one can do. MtGox can't protect users from getting their account hacked when it's nothing they've done. I filed a police report, but there's not much the police can do in the case of btc...
One learns from ones mistakes, so, now; stopped reusing passwords, and added two-way auth for important/sensitive things, alas, a bit too late (got 9 btc stolen ;_; although at the time, they were only worth ~100$/btc).