I've been using a Western Digital
The Root Hub powering down solution worked. ThanksIf Power Management is enabled in Device Manager for any/all of your USB Root Hubs, Windows might switch off your external hard disk when it detects inactivity to save power.
If you've invoked password protection software, when the drive restarts after powering down, you will be asked to enter your password again to unlock the drive.
Check all USB Root Hubs have their Power Management switched off and stop using the password software.
If the USB cable connecting the drive to your computer is more than 1ft (30cm) long, replace it with a shorter high quality lead.