I have a 97 audi A6 quattro with 135,000 miles. Recently the front passenger window has started to intermittently lower itself. It may go down an inch or two or lower all the way. You may or may not be able to immediately raise the window. Eventually I have alway been able to raise it back up. It may lower when driving or just sitting with the key on. I did some troubleshooting and got to the point that it is either the window motor itself or some part of the lowering circuit tied to the key locks. The window will lower on its own with the passenger side connector removed from the door switch which takes the switches out of the equation.