I have a MacPro, OS X 10.5.7. I have TM configured to back up to an external 1 TB firewire drive. I use Adobe Lightroom for photography. it provides a checkbox to allow you to backup all photos as you import them from your camera card. Adobe recommends selecting an external drive for these backups. But for some reason, it does not allow me to select the external drive that TM uses. Is there any reason why Time Machine might be preventing me from backing up photos to the drive, or to a new folder on that drive ?