While I was away, spammers had infested this forum. They made thousands of user names with their website URLs in their signature, and in their website field of their profile. Some even made fake posts with their website URLs appended to them.
After noticing a pattern that these spammers / bots use to register and update their profile, I specially designed a few SQL commands to delete these users and their posts from the forum database. The forum went from around 1700 users to around 200 users.
I tried to avoid deleting users that looked legitimate, but it was not an easy task. So if I failed I am truly sorry. Just register again if you wish.