There is a Javascript conflict between the RokBox popup and the Facebook Javascript Library. To fix, you'll need to edit the /modules/mod_sclogin/tmpl/login.php file. Around line 90, you'll see a section that starts with " // Alternative FB Login Buttons below. To use:"
Follow the directions in there to enable an image or text link button, instead of the Javascript-y "Login With Facebook" button. An image will work fine and won't conflict with RokBox.
Unfortunately, there is one other edit you'll need to make as well as the custom image solution has a minor bug of it's own when requesting permissions. In the /components/com_jfbconnect/includes/jfbconnect.js file, around line 25, you'll see:
}, {
scope:jfbc.scope
});Change the scope line to:
This last issue will be fixed in the 4.2.3 release coming out next week.
Hope that all helps, and sorry for the troubles!
Alex