I'm stumped. I've used NG15 for years on the same Dell D-630 laptop under XP-SP3 flawlessly. I've used a Seagate SRD00F2 3TB External HDD. I've read in Norton forums that NG15 won't read USB drives > 2TB, but it has been working fine all this time for me. Both for backing up a laptop image and having the recovery CD see the backup image for restoration.
Yesterday, NG15 stopped recognizing this drive as a destination. I've moved the USB connection to one of the right hand side (as you are facing the keyboard) USB ports, to a rear port on the Dell docking station and to a USB hub. Nothing seems to work. Rebooted several times.
Even more frustrating is that while NG15 can't see the external drive to choose as a destination for a backup, it *does* see the previous backup files on this external drive when I go to Manage Backup Destination. The drive doesn't show in either the Status and the Advanced sections.