My mouse rolls in several steps, and without any change on my side it shows this crazy rolling from time to time. It will will roll wildly for a minute or so, then stop until the next touch of the mouse wheel. Sometimes it starts at the second shot of a game and may continue with further games, too.
Solution is,
1) not to touch the wheel on the game screen (other windows are not affected),
2) to have patience until it stops - no clue how to stop it (?restart of browser or OS?).