The most likely thing is that the drivers have gotten lost. I'd suggest talking to Dell support; but they'll probably ask you to dig out your Windows installation disk, so you might want to see if you can find it before you call.

They may also ask for your "Service Code" which should be either on the setup CD or in your "Operating Manual." If you've called them before, they may have given you a "customer number," which speeds things up if you can find it. You can work around all these records with them, if you're persistent. They usually do their best to get you back in operation.

John