Unfortunately on my system testdisk says that backup and boot sectors are identical thus refusing to correct the problem. No idea of how this broken MBR found it's way to the backup. I definitely did nothing else before trying testdisk. It seems I need to rebuild the MBR from the Windows Disk now.
As Henri pointed out this bug should be of great concern to the developers. It was always a great difference to Windows that Ubuntu respects other OSs.
@Wetson, @Henri: your're welcome.
Unfortunately on my system testdisk says that backup and boot sectors are identical thus refusing to correct the problem. No idea of how this broken MBR found it's way to the backup. I definitely did nothing else before trying testdisk. It seems I need to rebuild the MBR from the Windows Disk now.
As Henri pointed out this bug should be of great concern to the developers. It was always a great difference to Windows that Ubuntu respects other OSs.