Dereck47 :
Go into Windows Disk Management and assign the 2 drives letters between M & Z. See if that works.
Thank you for the above suggestion. That was the first thing I did when this started...here is what ultimately resolved the issue. Was provided by support at Western Digital.
"I guess the disk is offline because it has a signature collision with another disk that is online.
In order to fix that issue, please follow the instructions below.
1- Go to START button, and right click on "COMPUTER" and Select "MANAGE" or find MANAGE on your system.
2- In this window, select from left side " Disk Management "
3- You will see your drives on the right side. (HERE YOU SHOULD SEE YOUR NOT WORKING DRIVE, it should appear as OFFLINE) you may have to look around for it , should I say look down to find it, the drive may not be on the right, it may be below the disk list, look around and down
4- Right click on "OFFLINE" tag and select "ONLINE"
(I am adding this notation: I reassigned the second drive a unique letter at this time. Then, with the drives still attached (I don't know if this makes a difference)...
5-Finally, Restart the computer.
By doing this process, the drive should work properly. " It did!