Private Sub Form_Load()
  Command1.Caption = "Start"
End Sub
 
Private Sub Command1_Click()
  With Command1
    If .Caption = "Start" Then
      <font color=green>' Hier die Start-Aktion einfügen</font>
      ...
      .Caption = "Stop"
 
    Else
      <font color=green>' Hier die Beenden-Aktion einfügen</font>
      Unload Me
      End
    End If
  End With
End Sub