Rhyn,
I just tried to register with JFBConnect again, but am being brought to the normal Joomla registration page. I'm not sure how you've configured this, but that's not right and likely won't create and associate the user to Facebook properly. Unrelated to the calendar question, but wanted to let you know.
As for the calendar, I couldn't see the issue since I wasn't able to login. However, I'm still not sure how we'd be able to fix this for you. The error is coming from JomSocial (I believe), and again, we don't have any calendar support. If there's any information you (or they) can provide about how we're conflicting, we'll gladly do what we can to fix it if we can. Without that information though, we'd have to tear about the JomSocial code to figure out what might be going wrong, and I'm just not familiar with their stuff. Additionally, this is a very rare error, which one other user reported, but it sounded like it wasn't an issue with JFBConnect in that thread I linked too.
Sorry to push it off, but our best suggestion is disabling or re-ordering other plugins until the issue goes away. Once it's narrowed down, we'll gladly help investigate if the problem is with us and fixable, but without it, there's not much we can do.
Thanks,
Alex