Please help! Ok

Please help! Ok. So about 2 months ago my window started acting funny. The drivers side front window. It would have no problem going down, but took some fiddling with the button to finally get it to go up. It worked a lot better and faster when the car was warm or warm outside, then after a couple weeks it stopped going up completely. So I had the window regulator and regulator motor changed, but then when you pressed the button either way the motor would only turn one way. After checking the wires from the switch to the motor I found that the polarity was only positive either way, or negative if I reversed the meter. So I replaced the console button. And blamo it worked perfectly for about 2 days until the first cold day below 50 degrees. Then it stopped going up until the car was fully warm or it got warmer outside. An additional problem that is really giving me a hard time (i had noticed it before the initial repair but forgotten about it) is that every time I open the door the window comes down a little bit to unseal, but no matter how far down the window already is, it still comes down a little bit every time I open the door. The passenger side window does not do this, it only unseals if the window is all the way up. I just can't figure it out and my bmw master mechanic keeps telling me its the regulator motor but i've checked it again and again, it works and its getting power correctly. Please help.