If your windows are the extra thick windows, they are de-laminating. There is not a good solution. I have the same problem. BMW said they would make me a deal, they wanted $6,000 to replace the four windows. Better solution, is replace the entire door. I have replaced two doors with the thinner, standard window which will not de-laminate. A new thicker window will just de-laminate again. The doors with the thinner windows are the same size and will fit just fine. Just a little tough to find a door in the same color. I used the interior panels from my doors and put them on the replacement doors. I have replaced 2 so far.