Also what if someone other than me logs into their account while logged into my home wireless network? Or what about those of us that log in from work. At one time there were three members here in my office (we've downsized enough that there's only me now) On occasion I've shown for sale ads to co-workers and if one of them signs up to reply are we both going to be booted?

Seems to me that a reflexive ban without any sort of investigation will hit more "false positives" than anything else.