I had a popping noise when I rolled the drivers window up or down. It got rather loud and was concerned maybe something was going to break. So I went to the dealer to get it checked out, The took off the door panel and found the some screws etc had come loose, they went thru the regulator ect and tightened all they could find. The noise is no longer there, SO if you have a metallic popping sound when the window goes up or down,Get I checked out. may save you a broken window or even more.