We were hacked over at the motorcycle site too, back a few weeks ago.
A troll used someone's account to perform his dirty work, then he deleted the member's account. I had to call the gentleman in Rhode Island, and explain the details to him.
We opened a new account for Him, and allowed him to post his butt off to make senior member again.
Meanwhile, I combed the membership data base and found not only him, but another bunch of trolls embedded into the site, (prolly back when the previous owner used auto sign up). I removed them (found them via the ICQ number category), and shortly afterward, My p/c contracted a virus as a result.
One dirt bag posing as a member, had a virus code attached, which sped up the hard drive to failure. However, I had dual hard drives, plus I was able to retrieve all My data from the first drive.
I repaired the old girl, but realizing that she needed some rest time, I bought a new pc on black friday, complete with windows 7, which is nothing but a warmed up version of vista.
My advice to forum admins is to watch the signature boxes on new registrant's profiles for tiny, (almost invisible) code. We currently screen all registrants with net tools, even before We send a request for contact info. Also, if You are not already checking emails addy's and IP's, here's a valuable FREE tool resource for that purpose:
http://network-tools.com/
~ Izza