This error presents itself when a couple of things happen.
1. Your forum cant contact the remote database in the allowed period of time
2. Our database is down (cough, it happens, I blame Russ

)
3. Youve exceeded the (newly implemented) limit of 5,000 queries in a 24 hour period (which is unlikely).
Are you using cURL for doing the queries? Its one of the options in vbStopForumSpam configuration. With cURL, you can control the timeout time window a little more but thats often at the cost of risks a "mysql has disapeared" error.