Thanks for the credentials. I was able to look around your JFBConnect and general Joomla settings and most things look configured correctly, though there are a few oddities mentioned below.
After checking the settings, I tried to login with Facebook and saw the issue. Then, I created a standard Joomla user using the normal registration process. After activation, I still wasn't able to login. After that, I disabled all of the JFBConnect plugins (authentication, content, system, and user) and still couldn't login with standard Joomla credentials.
The only way I can login is using the Super Admin credentials you sent to me. So, I'll definitely agree that there's a permissions problem. In the Global Configuration -> Permissions area, "Registered" the "Site Login" setting is enabled, but obviously still isn't working. However, I *temporarily* switched the "Registered" group settings to have "Super Admin" enabled. Once I did that, I could login both from Joomla credentials or JFBConnect. So, something on your site is restricting access to only super admin credentials. I have no idea what that would be (either a security extension or a database problem/bug), but that's as narrowed down as I can get.
Things I noticed:
* You have SP Upgrade installed on your system. Did you migrate from Joomla 1.5 (or 2.5) to 3.0? If so, it's likely possible the problem(s) were introduced during the migration.
* If I go to Extension Manager -> Database, there are 4 errors with your database. Clicking "Fix" should correct those db problems, but may not fix the overall access problem. The fact that there are errors may be indicative that there is an underlying database misconfiguration that's the cause of your issues.
I hope this helps get you started. Again, JFBConnect does seem to be working normal since it works when Joomla login works. There's definitely a permissions issue underneath that's causing both to fail. JFBConnect does not modify permissions or global settings *ever*, so this is not caused by JFBConnect.
Thanks,
Alex