Hi Andrew,
An explanation for this problem would be that many cd burning apps
(Nero, Adaptec etc) will by default disable auto notify. This is
because if a request is made to read the contents of the drive when a
cd is burning the operation could fail leaving you with a coaster
(wasted cd). In disabling auto notify the burning app is able to take
control of the drive and lock it from taking instructions from windows
while the cd is being created.
While this is a good thing it does stop autoplay from working on every
drive in the system.
The teltale sign of this would be that in explorer the cd name does
not update when you change discs, it stays with the same cd name as
when windows is booted up.
Having said that, I recovered autoplay by going to Windows Explorer,
right-clicking on the CD-ROM drive, choosing properties, going to the
Autoplay tab, and selecting play music CD with Windows Media Player.
Good luck