I've seen updates to the OS that seem to wipe this out. It's a nice thing to see but if the security tightening up has broke it then I would not second guess this.
You can try dell.com, put in your service tag and see if the drivers and apps for your machine have been updated.
When I first bought my computer (Dell Inspiron 1750 w/ Vista Home Premium), I could push the Volume controls, the wifi on-off button, or the screen brightness buttons, and I would see a little notification box pop up on my screen. It would stay on for a few seconds and then disappear again. None of these work now. It is sort of annoying not knowing whether my wifi is on, how bright my screen is, or how loud the volume is. Is there any way to turn these back on without reinstalling the OS?