title: Issue with cross domain forms authentication in IE
body: <p>We recently set up a series of sites such as <code>sub1.ts.se</code>, <code>sub2.ts.se</code>. We have wired them up with cross site authentication (asp.net mvc). Everything has worked as excpected. We have throughout the testing phase not ran into any issues, but as of launch, we are unable to login properly with IE.</p>
  
  <p>In testphase we use the auth cookie domain <code>.ts.se.production</code> (wired up through local hosts-bindings). This worked just fine. Going live, changing it to <code>.ts.se</code> wich is the live domain name, it does not work. When changing it back to the ".production", it does work! This is the same webserver, nothing else changes.</p>
  
  <p>Could this possibly be an issue related to the short domain name? I do know that IE have had issues with two letter domain historically.</p>
  
  <p><strong>Edit</strong>: The login error is that the auth cookie (wich does validate and set!) does not carry through subsequent requests/redirects, resulting in returning to the empty login screen.</p>