The Dirty -- FBI Launches Investigation Over Hacked Website

The FBI is on the hunt for hackers who shutdown Nik Richie's website The Dirty ... and the reality star tells us he's hemorrhaging money.

The Dirty has been down for weeks after a team of hackers began hitting the site with a DDoS attack -- which basically floods a server with so many requests it shuts down.

Nik tells us he contacted FBI investigators and they're on the case.

Richie says he's lost $250-300K this month alone in Super Bowl ads he couldn't deliver. He's also losing out because of cancelled appearances because he promotes them on his site.