I have a top member which has a strange username, it only consists of underlines (________). I don`t know if you have allready sorted the problem in 2.1 as I know you were aware of that username when trying to sort out my earlier issue.
Basically, this is the users profile under vbseo : http://www.radiomute.com/member-___________.html
Here is a search with this users posts
He tells me his control panel doesn`t work either.
It`s a strange case, but I hope you can fix it somehow.