I don't allow members to edit their publicly displayed names. Once in awhile I'll get a request for a change and I have always just edited the members 00000xxx.cgi file and reuploaded it....till lately.
For some reason if I edit the puclic name (line 16 I believe) the member can't log in anymore. They get an error saying that the user name doesn't exist. I can still pull them up in the control panel but their post have no avatars, titles or info. The post do take on the new public name though.
Any thoughts on what may have changed to cause this? I am on 6.1.0.4 and moved from a Windows host to a Unix host. I don't know exactly when it started doing this though.