Yes, this is a known issue. We're working on it.
The current workaround is to create an account on the Intel Developer Zone - since you're here on the forums you've already done that, unless you want to register with a different email than you used here (if that's the case, you'll need to create another IDZ account using that email).
Then, go to the Registration Center and log in using the same email that you had on IDZ. You should then be able to access and register products.
Edit: I believe this has been fixed now, and since the original poster hasn't responded, I'm going to assume their problem was solved and close this thread. If you have a similar problem please create a new thread so we can get to you in a timely and efficient fashion.