Just before Christmas I was driving along and my passenger window began to randomly wind itself down. Using the drivers side switch would not stop it but when the missus used the switch on the passenger side it did stop it from moving, and you could wind it back up but as soon as it was released the window would drop again. Rather than the usual single 'beep' when you press the button it would beep incessantly and the window would judder down a bit at a time. Now I've read about this problem on a few different threads but my situation gets a little more weird.
I figured that the problem must be with the drivers side switch so I removed it and disassembled and tested it. I found that the plastic membrane that goes over the board was badly worn and falling apart so assumed this to be the fault. I recently got round to ordering a new switch and fitted it last night. It worked fine to begin with, both windows working fine and the passenger window working using the passenger switch; today though the problem has reemerged. The passenger window has been constantly juddering down again, the window will wind up from the passenger switch but not down and - here's the odd bit - every time you press the heated rear screen the passenger window drops. Then disable the rear screen and none of the switches work.
Phew. I am extremely confused, any help or suggestions would be grand.