I have this problem and it seems to be made worse when it's cold. When I had service look at it on my annual in July, they were unable to reproduce, so it wasn't fixed. I haven't experienced it for a while, even during the warmer months when I would regularly open windows, until this morning. As I was pulling out of the garage with the temperature around 30F, I noticed some cat hair on me and opened the window to toss it out. When I tried rolling the window back up, it would reverse at about half way up. I tried 5 or so times before grabbing it and helping it past that trouble point. It is no doubt caused by an overly sensitive safety reverse and some kind of internal resistance. I'm planning to schedule service maybe in January to take care of this, a sunroof issue that they've tried to fix three times already, tire rotation, and the recall.