Useful link: http://www.howtogeek.com/howto/windows/find-your-missing-usb-drive-on-windows-xp/
Have you ever plugged in a USB drive or any external device with a hard drive and wondered why you cannot see it in My Computer?
More than likely the cause is that Windows renamed the drive to a
letter that is already in use. This will happen if you have several card
readers, thumb drives or external hard drives attached. It will also
happen if you are on a network and have mapped drives.
To find the drive and then rename it, you’ll want to right-click on My Computer and select Manage.
