Not sure why – perhaps drivers – but my Western Digital MyBook Essentials isn’t sleeping when connected to my PC – running Windows 7 x64.
It used to sleep when I had it connected to my Mac, but not anymore. I’ve searched WD’s website in hopes of software, but didn’t find any. Other than this minor issue, the drive works great.
I’d hate to unplug it every time I’m done with it… It must sleep on its own!