One of my DFW guys is having an odd issue and I'm not sure how to deal with it other than as you Admin types to check what he has to say and see if there is something that can be done to help him out...
I saw from the link you posted that my username isn't being used on the new forums, but when I try registering it, I still get a message telling me that it's already in use. When I go to the old forums, monogodo appears as being logged in, as it should, based on my settings. When I attempt to access the User CP to check my settings, and then select Edit Profile or Edit Options, I get a message telling me that I don't have permission to do so.
About the only solution I can think of would be to have the admins delete monogodo from the old database completely. Or possibly change my username on the old one, so that it no longer appears as monogodo, possibly by simply adding a number after the name. My guess is that somehow, the new one is accessing the existance of the old one, which makes no sense.