We've had about 2 reports of others not able to see their Overview page, but yours is the first that the actual error has been reported. Thank you, it helps to debug and diagnose the issue quite a bit.
JFBConnect uses a function called curl to make secure (SSL) requests to Facebook's servers. From the error you posted, it seems there's an issue with either your server or the request called out to Facebook.
Can you try, or answer, the following:
Do you have an SSL certificate for your site?
Can you try going to the overview page in both http:// and https:// modes to see if either works?
In the administrator area, go to Help->System Info and then PHP Information. Search for the area "curl". Please copy/paste all the information from that section back here. Nothing in there is private, but in case your worried, the main things I'd like to know are "curl support", "curl information", "ssl", and "protocols".
Sorry for the inconvenience, but we'll do what we can to help figure out the issue. It may ultimately require contacting your service provider for technical assistance, depending on if curl is configured in a non-standard way. Hopefully, we can find an easier work-around through our code though.