Too many redirects (loop)

We were using your plugin, until someday, it gives too many redirects to existing and new users when they try to log in with Facebook.

The app settings are correct (and based on the instructions) and are the same, like they were on the days that the plugin was working correctly.

Cant imagine whats wrong with this. We tried a reset at secret key, just in case, but nothing happens.

Any ideas?

http://wordpress.org/extend/plugins/nextend-facebook-connect/