Using Ultimate Facebook Registration with a brand new and empty WP installation 3.5.2 fails.
How to reproduce:
1. Log out of Facebook using IE10
2. Delete cache and cookies
3. Go to wp-admin of WP
4. Click the Login with Facebook
5. Popup for FB credentials appears
6. Enter email and pw and click "Anmelden" aka Login
7. The popup closes and the FB loading stays - no redirection happens.
If however you are already logged into FB the login and redirect works.
Please support to fix this bug.