' Beispiel: C:\MAPPE2.XLS (richtig!) öffnen
Dim bExists As Boolean
Dim oWorkbook As Object
 
' Prüfen ob Datei bereits geöffnet ist
bExists = False
With Application
  For Each oWorkbook In .Workbooks
    If UCase$(oWorkbook.Name) = "MAPPE2.XLS" Then
      ' Jetzt aktivieren
      Windows(oWorkbook.Name).Activate      
      bExists = True
      Exit For
    End If
  Next
End With
 
' Mappe neu laden!
If Not bExists Then
  On Error Resume Next
  Workbooks.Open Filename:="C:\MAPPE2.XLS", ReadOnly:=False
  On Error GoTo 0
End If