I'm surprised that no one has jumped in on this yet. Unfortunately, this is a common problem with 2000 and newer Cadillac DeVilles. It has been covered extensively on this and other boards before. If you own one of these cars long enough, it is not a matter of if, but when you will encounter this problem. Eventually, you may have to replace all 4. I have had 2 of them go already on my 2001 DTS. I'm not really clear on the mechanics of it, but it has to do with the failure (breakage) of the white plastic tabs that hold the components together inside the door. Most who have experienced the failure hear a loud crack when they are raising or lowering the window, and then it stays in either the raised or lowered position. The more mechanically inclined on here have managed successful repairs on their own, after struggling with getting the door panel off. Many others pay the Cadillac dealership $500.00 to $600.00 for the repair, about half of it being parts. If you are adventurous, there is a company on e-bay that sells rebuilt units on an exchange basis for I believe around $160.00 or $180.00. I, unfortunately had to pay the dealership prices, as I was leaving on a trip the next day and didn't want to drive an 800 mile round trip with the drivers window down. I guess you could have an electrical malfunction, but if I were a betting man, I would guess it is a case of Cadillac's "dropped window syndrome."
Terry