'Prüfen, ob Laufwerk bereit
Public Function IsDriveReady(ByVal Drive As String) _
 As Boolean
 
  Dim OldDrive As String
  Dim Result As Boolean
 
  On Local Error Resume Next
  OldDrive = CurDir()
  ChDir Drive
  Result = (Err = 0)
  ChDir OldDrive
  On Local Error Goto 0
 
  IsDriveReady = Result
End Function

'Inhalt Laufwerk anzeigen
Private Sub Drive1_Change()
    Dim Drive As String
        Drive = Drive1.Drive
                If IsDriveReady(Drive) Then
                    Dir1.Path = Drive1.Drive
                Else
                    msgbox "Laufwerk nicht bereit!"
            End If