First steps would be to:
* Disable the Joomla caching
* Clear your browser cache
My best guess is that some old values from the previous version are causing issues. If, when all that is disabled, things work, then we can start re-enabling things. In general, we recommend using Conservative caching on sites. Progressive really is meant for specific types of sites with lots of dynamic content, just so you know (I can explain more if you're curious). JFBConnect should work fine in both modes though.
Keep me posted if that helps narrow things down and we'll help however we can.
Thanks,
Alex