Tim,
If you're using sh404SEF, in the configuration area, click on the "By Component" tab and set JFBConnect to "Skip". If you're using a different SEF extension, you'll need to set it to skip JFBConnect in whatever way you can. When SEF extensions change the URLs that are coming from Facebook, that can cause some problems.
If that doesn't do what you're looking for, let us know.
Thanks,
Alex