I suspect if a member was banned from a site running forum software - be it SMF or Vbulletin I suspect when the account was accessed a message would deny login and state 'you have been banned' or email admin re your account being locked.

Not always the case Marty. There is a mod for SMF (which we can't install) as well as vB called "Miserable Users". Basically it causes a pre-defined list of users to get server time-outs. That's possibly what happened here.

He he he...I can't wait to get vB!