Private Sub cbarMain_ButtonClick(ByVal nButton As Long, ByVal sKey As String, _
  ByVal bValue As Boolean, Button As Integer, Shift As Integer)
 
  ' Mit nButton ist das beschriebene Problem auch vorhanden
  Select Case sKey 
    Case "mnuExit"
      CLOSE_APPLICATION False, False, False, True
      Exit Sub
  End Select
  .
  .
  .
End Sub

Private Sub Form_QueryUnload(Cancel As Integer, UnloadMode As Integer)
  If UnloadMode = 0 Then CLOSE_APPLICATION False, False, False, True
End Sub