WebGuerrilla - 11:04 pm on Nov 1, 2004 (gmt 0)

I'd post a note saying that you are moving to a moderated format, and that the board will be temporarily closed until you can put together a quality Mod team. (make sure you ask for volunteers)

If it's a forum worth keeping, you will have some quality people step up. And the downtime will help get rid of the trouble makers.

If you can't get anyone to help out, then just dump it completely.