Dim oldfoldername As String = Nothing
 
 
 Private Sub dgvFolders_CellBeginEdit(sender As Object,
    e As DataGridViewCellCancelEventArgs) Handles dgvFolders.CellBeginEdit
 
        If e.ColumnIndex <> 1 Then Exit Sub
 
        Dim obj As Object = bsfolders(e.RowIndex).Row(e.ColumnIndex)
        If IsDBNull(obj) Then
            oldfoldername = Nothing
        Else
            oldfoldername = obj.ToString
            If Not IO.Directory.Exists(IO.Path.Combine _
                                   (basefolder, oldfoldername)) Then
                MsgBox("Der Ordner " & oldfoldername & " existiert nicht")
            End If
        End If
 
  End Sub
 
 
  Private Sub dgvFolders_CellEndEdit(sender As Object,
          e As DataGridViewCellEventArgs) Handles dgvFolders.CellEndEdit
 
        If e.ColumnIndex <> 1 Then Exit Sub
 
        Dim rowview As DataRowView = bsfolders(e.RowIndex)
        Dim obj As Object = rowview.Row(e.ColumnIndex)
        If IsDBNull(obj) Then Exit Sub
        Dim newfoldername As String = obj.ToString
        If newfoldername.ToLower = oldfilename.ToLower Then Exit Sub
 
        If Not CheckFoldername(newfoldername) Then
            rowview.Row(e.ColumnIndex) = oldfoldername
            MsgBox("Unzulässiges Zeichen im Verzeichnisnamen")
            Exit Sub
        End If
 
        If IO.Directory.Exists(IO.Path.Combine(basefolder, newfoldername)) Then
            MsgBox("Dieses Verzeichnis existiert bereits")
            'Einbauen: falls Oldfoldername = Nothing DBNull.Value setzen
            rowview.Row(e.ColumnIndex) = oldfoldername
            Exit Sub
        End If
 
        If oldfoldername IsNot Nothing Then
            oldfoldername = IO.Path.Combine(basefolder, oldfoldername)
            If IO.Directory.Exists(oldfoldername) Then
                'Bestehenden Ordner umbenennen
                Try
                    My.Computer.FileSystem.RenameDirectory _
                            (oldfoldername, newfoldername)
                Catch ex As Exception
                    MsgBox(ex.Message)
                    rowview.Row(e.ColumnIndex) = oldfoldername
                End Try
            Else
                MsgBox("Der Ordner " & oldfoldername & " existiert nicht")
                rowview.Row(e.ColumnIndex) = DBNull.Value
            End If
        Else
            'Neuer Ordner wird erstellt
            newfoldername = IO.Path.Combine(basefolder, newfoldername)
            Try
                IO.Directory.CreateDirectory(newfoldername)
            Catch ex As Exception
                MsgBox(ex.Message)
                rowview.Row(e.ColumnIndex) = DBNull.Value
            End Try
        End If
  End Sub
 
 
  Private Function CheckFoldername(fn As String) As Boolean
        If String.IsNullOrWhiteSpace(fn) Then Return False
        Dim ivc() As Char = IO.Path.GetInvalidPathChars
        For i As Integer = 0 To fn.Length - 1
            If Array.IndexOf(ivc, fn(i)) >= 0 Then Return False
        Next i
        Return True
  End Function