title: Login challenge missing after migrating asp website from .net 2.0 to 4.0
body: <p>I'm upgrading an old internal website from .net 2 to 4 using <a href="http://msdn.microsoft.com/en-us/library/dd483478.aspx" rel="nofollow">this procedure from msdn</a>.
  I mostly got rid of .net assembly references in the web.config and switched the DefaultAppPool. However when I tried to access the website  using <a href="http://localhost/" rel="nofollow">http://localhost/</a> the login challenge didn't show up.  <code>Request.LogonUserIdentity</code> Is being used to get credentials. </p>
  
  <p>When I use http: //localhost/auth.aspx  the Challenge <em>does</em> come up. IIS manager has the auth.apx page set as default and I know for a fact it's being used, but the authentication doesn't show up unless I directly address it. </p>
  
  <p>Any ideas as to why it would only work when i type the full address? (If i go back to using .net 2.0 the request shows up without the full address, it only seems to happen on 4.0)</p>
  
  <p>did <code>Request.LogonUserIdentity</code> change from 2.0 to 4.0?</p>