When I switch off or unplug a Samsung External HDD on a Windows XP Home PC it automatically reboots. I have verified the settings for the HDD in Device Manager/Policies and it is set for 'Optimise for quick removal' and the cache is unchecked. I have looked at the ASRock mobo BIOS and it is not set to boot from any USB devices. Just HDD and DVDRom drives. It does not happen with memory sticks. The only way is to right-click on the system tray and 'stop' and 'disconnect' that way which is reasonably elaborate. Any ideas?