I think this may be related to the preview post bug...
I just found out that the allow special characters in the users names isn't being picked up by the system. I just tried to create an account for a user that was having problems and entered his name first [space] last name. Of course the system didn't like the space being in there.
Has this been found elsewhere?
Scott Cargill -WebMaster
East Hills Kung Fu San Soo