WP-FacebookConnect Plugin Login Issues

I’m using the WP-FacebookConnect plugin http://wordpress.org/extend/plugins/wp-facebookconnect/

When logging in to post a comment the plugin doesn’t seem to redirect back to the page correctly. Instead it redirect to the root of my website and adds a massive query string starting in “session=” .

It doesn’t seem to be able to create a session? What could be causing this.

I’m running the exact same plugin on another site and its working fine.