StoutFiles - 12:51 pm on Aug 5, 2011 (gmt 0)
Ban the rogue members by IP. Identify the rogue members and turn off their PM privileges. If they are squatting on a variant of your domain (which you should have purchased...) you may be able to email the domain name registrar to seek a remedy. Read their TERMS and CONDITIONS CAREFULLY FIRST.
I'm doubting the OP can do any of those things. It appears he/she just used a forum package and when it crapped out he had no idea what to do.
There's no excuse for a several month downtime. I suggest to the OP to learn some coding/server maintenance and be better off for it in the future. Two weeks of downtime is waving the white flag and you waited several months.