window motor or regulator?

It's likely the motor or the window switch. Check for power and ground to the motor and diagnose accordingly.

Well .... I've had the same problem with 3 windows in my BMW 323i , and each time it was about $250 to fix it. I took it to an auto body shop, ( mechanic at the garage didn't want to touch it ) they knew right away that it was the motor or a plastic gear in the door, can't remember exactly. They had to take the door appart to fix. Took about an hour to fix. Now i'm just waiting for the 4th window to stop working ...