David,
Your site is in offline mode now, so it's not possible for me to test.
When you say "Facebook logout", what are you talking about? Is the logout button on the SCLogin module just not working, or something else?
One setting to try toggling is in the Configuration -> Facebook area. Try turning on the "Logout of Joomla Only" setting. With that, the user will only be logged out of Joomla and not from Facebook.com as well. That uses less Javascript and so less prone to conflicts and may get you going.
I hope that helps, but if not, just let us know.
Thanks,
Alex