Has anyone experienced a problem with a buzzing sound in their passenger door? I didn't notice it until the other day while driving without the stereo on. It's a buzz sound (kind of like the sound of when you have a busted speaker when the stereo is playing).

It usually happens at speeds above 20mph; anything less, it doesn't make the sound. It went away the first time I heard it after I fiddled with the door air vent. However it came back and I can't pin-point it exactly, but it sounds like it is coming directly from the passenger door. I don't blast my stereo loud, even setting it at volume 8 is enough to mask the buzz sound. But when I have the stereo off, I can hear that annoying "bzzz bzzzzzz bzzz" sound.

It's really embarassing.