Sound when I scroll in windows apps

Seriously this is strange. In any windows app, when I scroll I hear this really faint grinding sound while I’m scrolling. But if I turn my speakers on really loud it’s kind of obvious. Can anyone please try this on your comp? Just turn up the speakers really loud and then scroll up and down in your web browser. I have Windows XP SP1, english.
Also, here’s a recorded sound of me scrolling up and down.