The drivers windows on both of my x5's are making the loud snapping noise as well. I have been tossing back and forth on replacing the window regulator as well. Some times they make the noise and other times they dont. I figure one day it will eventually fail but I think I will open the door panel up and have a look and decide if I can do the copper wire solution or just replace the window regulator. It seems like the loud snapping noise is a tell tale that the window regulator is failing.