New users can't register

I couldn’t find this issue witht he current WP/BP versions so added it here.
We’ve setup our network/multisite over the last 2 months. Using WP 3.1, Buddypress 1.2.8. Now we’re trying to get it active but new users cannot register.

It appears to the user that they are registering on the user side but they don’t get a verification email and the new user never shows up for us to approve on the admin side. They don’t get any error messages. Their IP addresses aren’t blocked. The verification email does not go into their spam folder.

User accounts may be registered IS selected.
Send the network admin an email notification every time someone registers a site or user account IS selected.
There are no domains or emails in the Limited Email Registrations or Banned Email Domains boxes.

I’ve removed any plugins related to user security, spam, or registration – except Akismet, BuddyPress, Multisite User Management, and SI CAPTCHA Anti-Spam.
Multisite User Management is setup for all new users to be Subscribers to our main site.
The users are on various networks and various IP addresses through out the city – using various email domains.

Here’s the site: http://fayettevilleforward.org/. Have no idea what else to check. Any ideas?
Thanks much.