Sleazy a similar thing happened to me
It may not be the same as what I had but I thought I would post this info just incase it is and hopefully save you a lot of headaches.
First get malewarebytes (
http://www.malwarebytes.org/ )and clean your PC then check all of your files on your server for either an Iframe that shouldent be there or other code that shouldent be there (its normally somewhere in the Index.)
Then change all your passwords ..including your email passwords (only after your PC is clean)
It is a firefox hack where they re-direct any logins to where ever they want. They got my admin password and all of my email accounts and changed the passwords
If you use filezilla to upload files to your server, there is also a hack for that. If malewarebytes does not pick it up delete the whole filezilla folder and any files associated with it.
I have norton running on my machine and it did not pick up shit so I now run both malwarebytes and norton