title: multiple login popups using windows authentication
body: <p>I'm am developing an application to use windows authentication.</p>
  
  <p>In IIS anonymous access is turned off</p>
  
  <p>In my web.config file I have:</p>
  
  <pre><code>&lt;authentication mode="Windows" /&gt;
  </code></pre>
  
  <p>and</p>
  
  <pre><code>&lt;authorization&gt;&lt;allow users="*" /&gt;&lt;/authorization&gt;
  </code></pre>
  
  <p>This works fine in the development environment, but when I deploy,
  some of the users get a windows login popup. Entering their user name
  &amp; password works, but sometimes they need to fill it in several times
  during a page load!</p>
  
  <p>Clicking cancel seems to be acceptable, and the pages load after one
  or more popups are dismissed.</p>
  
  <p>This does not occur on all client machines, it does not occur
  consistently on the same pages either - it all seems quite random!</p>
  
  <p>One user claims that he eventually had his NT account locked out after
  canceling too many times (I still need to verify this).</p>
  
  <p>I assume that the problem must be client-side, as it doesn't happen on
  every machine. Clients are using IE 6 browsers. Authentication is set
  to 'automatic logon only in intranet zone'.</p>
  
  <p>Any ideas what could be causing this?</p>