I was able to create a user with my Facebook credentials on your site and log out/in successfully (using Chrome). I didn't see the error that you're showing. Could you provide more detailed steps that you performed so that we can see the behavior in action on your site?
As a side note, I see there's an Autotune error for your site where there's another extension also loading the Facebook javascript library. Please check out our
Common Support Questions
for "I ran the Autotune Error Check and am getting the following error" to resolve this. Having multiple FB libraries included can cause unforeseen behavior with FB.
-Melissa
Load denied by X Frame Options facebook login
