Windows 7 Shutdown with MyBook NAS Online
I too was going nuts with my 64-bit Windows 7 freezing up on every attempted shutdown, if the MyBook World Edition II was powered up. Like Pejx72 (see earlier posting), I came to the conclusion that file system handling was causing the system to freeze as it waited for a shutdown acknowledgment from the MyBook which, of course, it was not going to get.
My particular MyBook appears only as a storage unit and a media device under the 'Network' tab in Windows Explorer. However, it also shows up in the "Disk Drive" category of the Device Manager window. I pulled up the context menu in Device Manager (right-click on the "MyBook World Edition Network Storage" entry) and selected "Disable" from the menu. At this point, Device Manager appeared to hang up, with the cursor stuck as an hourglass. I then went into the web page for the MyBook and powered it down, which freed up the hourglass in the Device Manager window.
After a reboot, the partitions on the MyBook are still accessible through the WD Discovery program and reconnect automatically in Windows Explorer. However, the disk has a "Disabled" status in Device Manager and my Windows shutdowns (Sleep, Hibernate, Shutdown or Restart) appear to be working normally.
My conclusion is that Windows was treating the MyBook as an internal drive, thanks to its entry in Device Manager, and this was causing the system to hang up when shutting down. I'll post here again if my solution doesn't stick. Interestingly, other computers who only accessed the network through WiFi did not appear to have the same shutdown problem. Perhaps this has to do with the sequence of shutdown activity, with WiFi going down before the file system tries to.