I've noticed in XP that never quite fixes it. Even if the Dot is in the top option, sometimes Autoplay even fails to bring up the main window.
Try this pastorjay:
Go to Start > Run and type gpedit.msc and click OK
In the new window, go to User Configuration and click the +
Under there, go to Administrative Templates and click the +
From there, click on the actual System FOLDER and look on the right side pane for Turn Off Auto Play. Double Click on that option,
Chage the option to Disabled (mind you, this disables the "Turn Off Autoplay" feature so that Autoplay DOES work, if that's confusing enough)
Reboot when you've done that just for effect.

See if it works. Another thing you can do, is go between the settings. Choose "Enable" then reboot, and go back and disable it, then reboot to see if that fixes it.
Aside from that, there's not much else I can think of that would fix the autoplay problem - you might want to download the Windows XP Compatibility Patch from Windows Update as well.