You're most likely using Joomla 3.0.x. JFBConnect is no longer compatible with Joomla 3.0. Please upgrade to (at least) Joomla 3.1, or 3.2.1 (recommended).
Joomla 3.0.x has multiple known security issues and bugs that we no longer could work around or support. Upgrading to Joomla 3.1 or 3.2 should be a 1-click process using the integrated Joomla Updater extension.
I hope that helps, and sorry for the inconvenience. If you need anything else, or have any further issues, just let me know.
Thanks,
Alex