Cant explore in start menu

In Windows XP Pro SP1 (OEM):
- Click on "Start" then right-click on "Programs" and click explore : it works.
- Click on "Start"->"Programs" then right-click on "Accessories" and click explore : it doesn't work :( .

The problem: Right clicking on any start menu item inside "Programs" shows the "Open", "Open All Users", "Explore", and "Explore All Users" but selecting any of those items does absolutely nothing. This worked perfectly fine in Windows 2000 Pro.

Any suggestions?

(P.S. This isn't the problem that can be fixed by enabling all drives inside TweakUI. The items themselves are NOT greyed out and look as if they would work.)