Quick fix: go back to www.rcadvisor.com, logout, and login again. The forums should now know who you are and everything should be working.

Longer explanation: The forums run as an entirely separate application from the rest of the website. They maintain their own user registration information. A module on the main website copies your user registration data between the two systems. If you registered on the main site before May 17, 2008 and use cookies to stay logged in, the forums may not know who you are.