Registration Process Issue

I'm having an issue with the registration process with Membership...

When a user tries to register, they fill out the information in step 1 and get directed to step two. However, step 2 never completely loads in the page and redirects back to step 1... If user tries to re-enter their information again in step 1, they get the "username is taken" response...

Now, the partially registered user can login and go to the "Join" page where they can select a subscription level...

Please take a look for yourself at http://www.thescootclub.com/join-scoot-club/

Any insights here would be greatly appreciated...
Thanks in advance.