Sounds like a User error trying to make root a QB user and then deleting said user..... that being said user message system would be a good thing to add to the QB-Pro version i think but i dont see it being added in the current version. though there is a plugin you can install for rutorrent for chat. and we also make installing irc clients easier.

Though if i am wrong @JMSDOnline will surely correct me as he does often lol

QB user root I have created and deleted myself to test it.
and that works.

@Sub-7 QuickBox Pro will and does currently implement this. However, it will still be up to the systems administrator to include the proper blacklisted usernames. Give me a few common ones you'd like to see included and I can have them insert to the database on install.