April,
Please let me know what profile plugins you have enabled, and also try disabling them to see if that fixes the issue. It obviously shouldn't be the problem, but what I see when I try to register is something I've seen in the past when our integration with other extensions breaks for some reason.
Obviously you have Kunena installed (and I'm assuming the JFBC profile plugin as well). If disabling that works, let me know what versions of Kunena and the profile plugin you're using. If it's a different plugin that's causing the problem, let me know the version of it and the extension it integrates with as well so we can investigate further.
Thanks,
Alex