This is a well known problem on these cars.
So much so that if BMW were righteous about it, they'd do a re-call. I've had both the window motors replaced on my 03 Mini and they're starting to act up again.
It starts out with the solenoid clicking and windows not dropping when the door is opened and gradually progresses to total failure. Problem is, my Mini will probably be out of warranty when they go out completely and unless they can duplicate the problem. no fix under warranty
