If you like, I can have a verification email sent to you that will end up giving you a temporary password and letting you log in. That has cleared similar issues up for some other members. It won't explain why it's not working, but it may fix it. If you want me to do that IM me your email address if it's different than the one on the account currently.
I'm having this very same problem and recieve the same error message as MSeng . I'm trying to update my e-mail address, but it will not allow me to do so.