Please see this page: http://heavybuzz.com/contest_view_completedcontest.php?contest_id=8
This page has a facebook comment box that is inside of an i-frame. It shows great in Firefox but will not show at all in Internet Explorer.
I have IE8 so I am not sure about other IE versions 6 or 7 but I know this is a known problem in Internet Explorer. I need patch to make this show.
