For information (I am not looking for any help):
I had an old version of Twonky on my white light which I upgraded to Twonky 6.0.3 (I downloaded directly from the Twonky site). It worked perfectly except for the fact that the disks would not spin down any more. I checked that it was not updating log files or the DB when I should have been sleeping (I checked every file on the system for a timestamp that would have prevented sleep) - but found nothing. On the twonky forums I found at least one other person that had the same problem with their NAS (not a MBWE).
So I downgraded to the latest version 5 which is 5.1.6 (still an upgrade from where I originally was), and Twonky functions perfectly and the MBWE sleeps just as it used to. I notice that MBLive comes pre-installed with 5.1.9. Maybe version 6 not ready for NAS yet.
[sorry - maybe I should have placed this in "Installing & Configuring Programs" - I don't know how to move it]
Hope this helps someone.