Assuming that you have checked the autoplay settings on the drive's property card, all I can offer is sympathy. I've been using xp pro for 2 years and have had the same problem sporadically. Sometimes it works perfectly, then at other times is does nothing at all, regardless of the settings.
I recently burnt a music cd using Pinnacle`s Instant CD/DVD SE VERSION 7 after which my drives no longer Autoplay. Having checked the Registry as Pinnacle`s support suggested and found all as it should be, i`m at a loss to solve this problem. I`m running Windows XP, thanks for any help.
Pete.

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic