Marketing_Guy - 3:58 pm on Aug 5, 2011 (gmt 0)
This kind of stuff is more common than you think so try to not to feel too hurt about it. To be honest, the Internet, particularly discussion forums, seems to have a magnifying effect on people's dominating personality traits and for many it brings out some really bad sides (sometimes unintentionally).
If your domain name is in anyway unique then put in an application for a trademark and go via the domain name dispute process mentioned earlier. If we are talking serious levels of money involved then their public claims "the site has now moved to the .org" could be considerd to be them "passing off" their website as yours / your business. You'll need to prove your business has been hurt from this, etc and you have claims to the name though - generic keyword domain names won't leave you with much ground to stand on.
All that aside, it would probably be best to reassess your forum management policies. In my experience (and I've been through similar things), the problems stem from deep issues that need to be changed. Perhaps you were too hands on dealing with people on your forum, perhaps not enough. Maybe your guidelines were too strict or not specific enough. Maybe you dealt with your mods in the wrong way, maybe you didn't.
But regardless, as a forum owner anything that goes wrong or any negative feelings about the site are immediately associated with you, regardless of your blame, efforts, good intentions, whatever. Been there many times lol! :)
Cover yourself legally and use whatever technical means you can to plug the hemorage of members (no PMs for new members, etc). After that it's just a case of improving on your site. At the end of the day, you had the forsight and motivation to setup the forum - your ex-members just had a bug up their backside and decided to copy you. Don't waste your time on them.