"nails on chalkboard sound" when lowering pas.window.

[tjct]

2007 328xi coupe. sounds like a grain of sand is stuck in the rubber channel the window pulls through when lowering the passenger window only during the first 3" of travel. Looks clean and treated the rubber with a vinyl/rubber protectant. No help. Sounds terrible,but It`s not scratching the glass. Any ideas?

[adc]

2007 328xi coupe. sounds like a grain of sand is stuck in the rubber channel the window pulls through when lowering the passenger window only during the first 3" of travel. Looks clean and treated the rubber with a vinyl/rubber protectant. No help. Sounds terrible,but It`s not scratching the glass. Any ideas?

Happens to me, but not every time. Couldn't come up with a pattern.

But mine also leaves some white residue on the windows, perhaps grease mechanism?

As soon as it will happen again, I'll take it straight to the dealer. Obviously something's rubbing.