Welcome to the community, lightslayer!
I'm sorry to hear about your detection issues with the WD My Passport drive.
Could you, please, tell me how does the external HDD appear in Disk Management and Device Manager? You could try assigning a different drive letter to it and see if it will be recognized properly afterwards.
Here's a tutorial from our knowledge base that explains the step-by-step of the procedure:
http://products.wdc.com/support/kb.ashx?id=64Attq
Give it a try and let me know how it goes!
SuperSoph_WD