My intranet based scenario is end users will be authenticated by AD.  When they hit my Umbraco site i will take action based on who they are.  This is not a problem.  What i find puzzling is why when enabling Windows Authentication (disabling Anonymous), upon the first page view i get redirected to login (actually page not found because i haven't made a login page).  

Upon the very next request, i get the expected behaviour ie the web site appears fine.  I get some stylesheet issues which disappear on the next page refresh, probably for the same reason why nothing works the first time round.

I'm expecting the ServerVariable  AUTH_USER to get passed because Windows Authentication forces it to be.  The contents of it appear as expected on the 2nd page request, but presumably not on the first which is why i'm being redirected to login?

I'm using IIS Express, which i've configured for Windows Authentication only.  If i leave Anonymous turned on then the issue disappears (as i would expect) but then i dont get AUTH_USER passed at all as the browser doesn't seem to bother sending it.  I find this behaviour disappointing....

Can anyone help?