WD External Hard drive not recognized in my computer

I am running Windows 7 home premium on a HP DV6 notebook. When I plug in the WD external HD via USB, the windows explorer does not  recognize the WD HD. I used  Paragon Partition Manager 10 to look at the issue. The computer recognizes the WD HD but there are no drive letters assigned to the partitions in the WD HD. After assigning drive letters, I can use the WD HD.

I am looking to find a permanent fix for this issue and will post it leter.