I had a lot of trouble getting my W7 laptop to recognize My Book. I dual boot W7 and Linux Mint. LM recognized My Book OK BUT this was because in LM you actually include details in the FSTAB file. Then I realised what the problem was. My Book shares are configured with Users and Passwords and I had recently changed the password on my laptop. I restored the old password and now all is well. Make sure that if you change one of your passwords, you need to change all your PCs and ALSO My Book.
Thank you for sharing this information. Hope it helps other users.