title: System.DirectoryServices.AccountManagement.PrincipalContext broken after Windows 10 update
body: <p>I've been using this little function without any issue for the past few years to validate user credentials. The <code>createPrincipalContext</code> method returns a <code>PrincipalContext</code> with <code>ContextType.Machine</code> and the machine name.</p>
  
  <pre class="lang-cs prettyprint-override"><code>public static bool ValidateCredentials(string username, string password, string domain = null) {
      try {
          using (var principalContext = createPrincipalContext(username, domain)) {
              username = GetLoginInfo(username).Username;
              // validate the credentials
              if (principalContext.ValidateCredentials(username, password)) {
                  //once valid check if account is enabled
                  using (UserPrincipal user = UserPrincipal.FindByIdentity(principalContext, username)) {
                      return user.Enabled.GetValueOrDefault(false);
                  }
              }
          }
      } catch (PrincipalOperationException e) {
          traceError(e);
      } catch (Exception e) {
          traceError(e);
      }
      return false;
  }
  </code></pre>
  
  <p>My development machine automatically updated to the latest version of Windows 10 this recently, and since then, <code>principalContext.ValidateCredentials</code> has been throwing the following exception.</p>
  
  <blockquote>
    <p>System.IO.FileNotFoundException: The system cannot find the file specified.</p>
  </blockquote>
  
  <p>Other than the machine update nothing else was changed. I've spend the last few days searching the net for what may have caused the issue.</p>
  
  <p>Does anyone have any experience in identifying what may have been the cause and if possible, a solution?</p>