You are going to laugh your butt of when you read this but this honestly happened to me just last week.
The computer would start making a funny sound and the page on the screen would scroll quickly down to the bottom and be stuck there. Using my mouse I could pull it back up with effort but it would shoot right back to the bottom as soon as I tried to click.
I discovered that my breast was resting on the ctrl, fn, and alt keys and when I leaned back in the chair the problem went away. Okay, you can laugh now...but it's true!