Do you have any Facebook Channels setup for the user you're trying to authenticate with? When you setup a Channel, there's some extra permissions we request of the user, which could be causing the reload loop.
Beyond that:
* If you turn off the Auto-Login feature, does normal login with Facebook using the blue button work as expected?
* Can you test with another Facebook account to see if it runs into the loop?
Keep us posted and we'll do what we can to help.
Thanks,
Alex