I created a Facebook Canvas page using Facebook C # SDK 5.0.25. Unfortunately, when I use IE7, then the user is redirected to the page "/? Fb_xd_fragment", and as a result, he views a blank page.
See http://bugs.developers.facebook.net/show_bug.cgi?id=9777 and https://developers.facebook.com/docs/reference/javascript/FB.init/ for a possible workaround for this problem.
In particular, you need to provide channelUrl back to your page.
See also this question , which contains some useful sitelinks.