I thought it was a helicopter but it turned out to be my hard-drive.
My computer is officially going to explode. My mouse is wire-short suiciding in sympathy.
This is more than slightly worrisome. There’s no more pretending that a full wipe is going to fix it. Anything that grinds that loud, enough to give the illusion of blades chopping the air thirty feet above my building, is on its way out.