Social Theme Customization - and now can't register any new users (even without plugins)

Hello,

I had a pretty heavy visual custom job on the Social Theme done for my BuddyPress site.
(Hired somebody on Odesk for it.)

See test site here:
http://jazzheavenproducts.com

Running latest WP MULTI-SITE, latest BuddyPress, latest Social Theme (and customized child theme).

But now I realize one can not even register...%^&*(

Site acts like it registered the new user, but then no email to user, and no new user visible in WP backend.

I then tried to register with the exact same info (since no user with that info shown in WP backend), and, when I chose the SAME BLOG URL to be created (again, it's a WP MULTI-SITE, so new users have the option to create their own blog on the site), the system tells me that Blog URL is already taken - so the system at some level DID store that there was somebody trying to register...
See screenshot here:
http://jazzmusicheaven.com.s3.amazonaws.com/images/falk-temp-images/error-screen-thejazzhang-reg-attempt.JPG

Even when I disable all plugins, this stays this way.

Even when I switch to the DEFAULT BUDDYPRESS THEME, this stays this way (new users can't register).

SIDE NOTE: even when I activate the default buddypress theme, I do NOT see the regular BP theme, but I see a lot of the visual customizations there were done.
IS THAT NORMAL? SHOULDN'T THE CUSTOM STUFF ONLY SHOW on my Social Theme Child Theme??

Anyway, it seems like this issue of users not being able to register must have something to do with the CUSTOMIZATIONS, agreed?

If the Social Theme itself had that issue in general, I am sure a lot of users would have mentioned this on this forum.

Any pointers appreciated.

Thanks in advance!

Falk
SHOULD