This is most likely because of the changes that were made when we upgraded the boards. It used to be that your username and password for the forum was separate from the login and password for the store/general WTM account, so some people had different emails, usernames, and passwords for each. Now, one account is used for both the store account and forum access, and that account is established by email address. You may have had an older email associated with an older profile that got "chosen" by the system as your account. Your old profile is still there. It just needs to be merged with the account (and forum profile) that is established now.
I am going to go look into this. It should be an easy fix, but I may need to contact you for additional info. I will update you shortly.