I've been hearing people are having issues registering where when they click register, the page cycles back to a blank registration page.
I've found these people are usually registered, but never receive an activation email.
I tried registering another account.
The only issue I saw was the security string (scrambled letters was missing) so I clicked to request a new string.
Registration went fine and received the activation email.
I went to the admin panel and re-saved the settings.
The string now appears.