private bool mSuppressEvents = false;
Private Sub TextBox1_TextChanged(ByVal sender As System.Object, ByVal e As _
  System.EventArgs) Handles TextBox1.TextChanged
  if Not mSuppressEvents Then
    mSupressEvents = true
    try
    {
      If TextBox2.Text = "" Then
      TextBox1.Text = ""
      TextBox2.Focus()
      MsgBox("Stopp")
      mSuppressEvents = false
    }
    finally
    {
      mSuppressEvents = false
    }
  end if
End Sub