Thanks Mabkey. The drive shows up as healthy, with drive letter O, only after the PC has been rebooted. If I unplug the drive (from the USB port), and then plug it back in, it will not show up at all in Disk Management or Windows Explorer until the PC has been rebooted, although it does show as a disk drive in Device Manager (as WD MyBook 1111 USB Device). To get it to show up in Disk Mangement or Win Explorer, I have to reboot. This does not happen on the Win7 machine. There I can plug and unplug the drive, without any trouble. This is a new problem , starting a few days ago.
Alan
