Undo the underside of the mouse, remove the rollerball, clean it with a wet-wipe tissue or similar, dry off with a kleenex tissue, replace, and re-fasten the underside, and it should work OK. If not, suggest buying a laser mouse, they only cost about �5, and work brilliantly. Hope this helps
okay... incase your not being saracastic... its because as a defaul setting the wheel acts as the scroll button so as you roll it down the scroll bar goes down and the opposite for when you roll it up. you can change the options if necessary