Give another browser a try. Often, after logging in, your browser is still caching the old version of the page. We’ve shut off most of our server-side instructions to your browser. Try a Shift+Refresh, or an alternate browser. Also make sure you don’t have a proxy or something sitting between you and us, caching old pages. Tell your browser to dump its page cache (but not cookies) after logging in, if possible (Shift+Refresh does that in most browsers).
Not sure if its related issue, but unable to use Windows Live/facebook/google account to sign in to site. It gets struck at cross domain authentication add-in URL (below):
Tried shift refresh with no luck. Will try different browser and see if results are different. Currently using IE11