title: asp.net Problems with login : login failed for user NT Authority\Anonymous Logon
body: <p>Im getting the following error when I try to login to web page with a valid username and password:</p>
  
  <blockquote>
    <p>Oops. The error: Login failed for user 'NT AUTHORITY\ANONYMOUS LOGON'.</p>
  </blockquote>
  
  <p>This is my web.config :</p>
  
  <pre><code>&lt;configuration&gt;
    &lt;system.web&gt;
      &lt;customErrors mode="Off"/&gt;
      &lt;authentication mode="Forms"&gt;
        &lt;forms name=".ASPXFORUM" loginUrl="login.aspx" protection="All" 
                                                      timeout="30" path="/" /&gt;
      &lt;/authentication&gt;
      &lt;authorization&gt;
        &lt;deny users="?" /&gt;
      &lt;/authorization&gt;
    &lt;/system.web&gt;
  &lt;/configuration&gt;
  </code></pre>
  
  <p>Anyone know what this error mean?</p>