Have you tried plugging the mouse into another computer? I plugged my windows mouse into a linux laptop and it was scrolling off the chain. One click would scroll more than one page, and it was out of control. I had to plug it back into the windows computer and turn it off or something to get it to fix itself. It has something to do with the scrolling resolution, and I'm not sure exactly how it works, I just know it keeps the scrolling resolution from a previous device sometimes.
If you have done nothing else, make sure you have the mouse plugged in and on and turn off your computer. Then turn on your computer.