title: .Net's Directory Services throws a strange exception
body: <p>I have a small C# solution used to check users credentials. It works fine for two of my teammates, but on my PC I get an exception.</p>
  
  <p>The relevant code:</p>
  
  <pre><code>PrincipalContext context = new PrincipalContext(ContextType.Domain);
  if (context.ValidateCredentials(System.Environment.UserDomainName + "\\" + usr, pwd))
       return true;
  else
       return false;
  </code></pre>
  
  <p>And the exception is:</p>
  
  <blockquote>
    <p>DirectoryOperationException, "The server cannot handle directory requests.".</p>
  </blockquote>
  
  <p>I tried creating context with the explicit server name and the 636 port number, but this didn't help as well.</p>
  
  <p>Any ideas?</p>