MyBook Essentials Listed in "Devices" But Not As Mapped Drive in "My Computer"

If you are using 2 identical drives at the same time it’s probably a signature collision. Does the drive show if it is the only one connected? It could also be a power issue with 2 drives. This explains fixing signature problem http://community.wdc.com/t5/My-Passport-for-PC/Copy-files-from-one-drive-to-another/m-p/277504/highlight/false#M7587 see post 11.

Joe