You should look at the wiring harness on the driver side window switch assembly and see if the ground wire(s) are well grounded. And you should check the wiring harness bundle from the grommet in the door to the grommet going into the car body - the frequent opening/closing of this door often fatigues the wiring and you may have one or more of the wiring with few strands still intact within the plastic insulation. These issues can be difficult to find.