We have had some reports about an FBI visrus being installed on peoples computers, we checked and its not coming from us but seems to be pre existing on members computers prior to visits. The FBI virus basically gets activated by high traffic tube sites and torrent sites and then displays a fake FBI message asking users to pay a find or they will get sued.
You can google
FBI MoneyPak Virus – Removal Instructions
and it seems there are alot of way to remove this, and even if you don't have the symtoms you should probably get a mal-ware removal program like
malwarebytes - http://www.malwarebytes.org/
In order to make sure you clean your system.