If I'm using IE8, and I try the "log in" link at the top right of the page, and try clicking the "login with facebook" button, it appears to only work reliably on the forum home page. From other pages (such as a member's profile), I get the "Internet Explorer cannot display the webpage" error page with the "diagnose connection problem" button.
If I try to log in from Kier's profile page, the URL that contains the "Internet Explorer cannot display the webpage" error is: http://xenforo.com/community/register/facebook?reg=1. If I refresh that page, it redirects me to facebook to log in.
At first I thought this was a corrupted cookie issue, but I can recreate it even after deleting cookies. If I knew how to interpret IE8's "diagnose connection problem", I could provide more data.
Could it be something wonky in my IE8 installation?
EDIT: Could maybe be a "headers already sent" error message? Which might explain why I can refresh the URL, and get redirected to the correct page? And fixed a typo