Recently, for no reason that I can figure out, my mouse scroll wheel suddenly became hypersensitive. I would scroll just a tiny fraction and the window in focus would scroll down as if I had spun the wheel harder than the burliest contestant on The Price Is Right. Reams and reams of virtual pages would careen before my eyes. I would try to barely move it - but it was like playing that Operator game -- and I kept touching the sides! BZZZZZZT!!! It was so sensitive that just the barest touch of my finger would send it down several pages. On several occasions, and I am not making this up, the damn thing would literally scroll UPWARDS after it hit the bottom of the page, as if it were bouncing back due to some kind of virtual scroll-wheel backlash.
It nearly drove me insane. I had to put a stop to it.
The problem was systemic to all applications, so it seemed likely a driver issue. After fiddling with the control panel, which didn't help because the slowest scroll speed was still 100 KPH or better, I went to phase two and upgraded the mouse driver. I installed the latest Microsoft Intellipoint mouse driver, and that fixed the issue without even requiring a reboot. Yay!
So the next time your mouse is giving you problems, try upgrading the mouse driver software. Or even just reinstalling the drivers you already have. Chances are good that this may fix your problem. If not, there's always tech support