Fatal error: Class 'JClientHelper' not found in

We've never seen that error. The file you mention is a core Joomla file, and not one from JFBConnect. The library it's trying to load, but failing, is also a Joomla library. I'm not sure what's happening there, but not sure how we can fix that in our code.

Can you let me know what version of Joomla you're using and what 3rd party profile extensions you're using (EasySocial, JomSocial, etc)? We'll gladly try to help determine things, but not sure where to start.

Thanks,
Alex