title: DirectoryServices.AccountManagement "old" password still validates after password change
body: <p>After resetting a users password in Active Directory, if the user tries to log in using their old password, the following code validates as True:</p>
  
  <pre><code>Dim up As UserPrincipal = GetAdUser(objContext, arg_strBA, arg_strUsername)
  
  If up IsNot Nothing Then
  
      Dim valid As Boolean = up.Context.ValidateCredentials(
      up.UserPrincipalName, arg_strPassword, ContextOptions.Negotiate)
  
  
      If (valid) Then strReturn = up.SamAccountName
  
  End If
  </code></pre>
  
  <p>We are resetting the password using the following code:</p>
  
  <pre><code>Dim objUser As New DirectoryEntry(arg_strLDAPPath)
  
  If Not objUser Is Nothing Then
      objUser.AuthenticationType = AuthenticationTypes.Secure
  
  
      objUser.Invoke("SetPassword", arg_strNewPW)
      objUser.CommitChanges()
  end if
  </code></pre>
  
  <p>The password reset works fine and the user can log in with their new password, but their old password should not still validate.</p>
  
  <p>When the above ValidateCredentials works for the old password, we are assigning the credentials to a web service call, which then fails with a "401:  Unauthorized" error.</p>
  
  <p>Anyone seen anything like this?</p>