This has happened to me before, turns out, it was a stuck key on my old keyboard. As soon as I unplugged the keyboard, the scrolling stopped. Check to be sure no keyboard key's are stuck. Also, since mice come with a scroll wheel, it wouldn't be a bad idea to unplug and re-plugin the mouse.
I have unplugged & plugged back my mouse and it stopped, also I have a mechanic keyboard so it's hard to it being the cause. Maybe I'am scrolling to fast.