To fix this you have to select all polygons of the window glass of the bugged windows and merge the polygons to one polygon. But be careful, this is only possible if the angles of the seperate polys aren't too different. If the difference is to big LW want merge them. For this case you have to flaten them before, but this could also have an impact to the whole fuselage!
thanks for the help, but I don’t know how to work with it!)