Hmm.. that is a strange one that we haven't seen. We're working hard on 3.2 right now though, so if there's something to fix, now's the time.
To start, can you give me the URL/path to the page that's throwing the 500 error? Don't need your domain name, just something like:
/administrator/index.php?option=com_content...
Also, are you including any {} tags in your article, either for JFBConnect or for any other extension that uses {} tags?
Finally, just to make sure, you're using normal Joomla articles, correct? Not K2, Zoo, FlexiContent, etc? Those shouldn't be a problem.. but if you're using them, it helps make sure we're looking in the right place.
Thanks!