36

On my Windows 7 system, and in all programs, when I scroll down with my mouse, it will scroll partway down then then scroll partway up. It is totally erratic and is driving me crazy.

I do have a wireless keyboard/mouse, but I do not use the mouse, as it does not work: I have replaced it with a "wired" mouse.

I have tried adjusting the mouse settings (number of lines to scroll, and turned off "acceleration, as I think it was called).

Does anyone know how to fix this?

8
  • Are you scrolling with a scroll wheel, or by grabbing and dragging the scroll bars? Jun 17 '11 at 0:19
  • With mouse wheel. Tried different mouse, and no problems.
    – bnieland
    Jun 23 '11 at 15:15
  • 1
    I hate to throw a "me too" onto this, but here it is. I have scoured the farthest reaches of the internet and have not found anyone with this exact problem until now. I'll try to come back and post an answer if I ever hear of one. Mar 20 '12 at 18:32
  • When you say that it scrolls back “someway” in the opposite direction, exactly how much do you mean, one click of the wheel or a lot?
    – Synetech
    Aug 29 '12 at 4:38
  • It's a "two steps forward, one step back" kind of thing.
    – Umopepisdn
    Nov 27 '15 at 19:47
6

I just switched the number of scroll lines from the default (3) to 5 lines and this seems to have stabilized the erratic behavior.

1
  • This helped me, but it keeps doing it when I scroll quickly.
    – jvriesem
    Sep 4 '15 at 5:09
34

It's dust.

No, really: it happened to me many, many times, and the cause so far has always been dust inside the mouse. It gets trapped in the scroll wheel and interferes with the sensors.

In order to solve it, open it and clean the wheel — or, if it's a cheap model, I recommend buying a new one.

10
  • 1
    Not if you're using an ergonomic mouse
    – autonomatt
    Jan 7 '15 at 16:35
  • 3
    I have had this happen a couple times - dust or crumbs is usually the problem (though it has been a failing component as other answers suggest). Try blowing into the wheel while rolling it (or better used use compressed air), this generally clears the dust without having to dismantle everything.
    – brichins
    Nov 18 '16 at 17:13
  • 9
    Wow i blew on it for 2 seconds and problem solved.
    – Ben
    Dec 24 '16 at 2:40
  • 2
    I must confirm that blowing on it a few times made it better, but didn't completely fix it. Compressed air is probably the best option. I doubt it will fix it for good, but it will make it better. For a permanent fix, maybe Synetech's answer would be better. Oct 5 '17 at 10:19
  • 2
    Blowing on it 2-3 times completely fixed it for me. Dec 13 '17 at 22:19
25

Assuming that the amount of back-scroll is only a single click of the scroll-wheel and not half-way up or down the page, then what you describe is typical of wheel-mice, especially older ones.

If you open a wheel-mouse and look at how the scroll-wheel mechanism works, you’ll see that it has a series of bumps inside the wheel and a spring that presses against the bumps to cause the click-y feeling. Moreover, you’ll notice a series of thin slits on the face of the wheel through which a small beam of infrared light passes, and the mouse detects the interruptions as the wheel rotating.

The problem is that the bumps inside the wheel (“resting positions”) are not always perfectly aligned with the slits. This can be exacerbated with age due to wear. As such, when the wheel is rotated, the mouse things it has stopped scrolling, but when you release the wheel, it settles in the bump, causing a slight rotation forward or backward.

There’s not a whole lot that can be done about it, but one option is to open the mouse and remove the spring altogether (the one with an end inside the wheel, not the one holding the wheel up). Personally, I find it better because then the mouse has no clicking at all and feels smoother. In fact, it is quite desirable because excessive clicking with some mice can create a big headache due to all the vibrations. The problem of course is that if the wheel is too loose, then it may spin too freely and cause its own erratic scrolling issue.

3
  • 2
    @bnieland: this should probably be the accepted answer. The currently accepted answer does seem to help, but this is a better answer.
    – jvriesem
    Sep 4 '15 at 5:09
  • 2
    When I disseambled my mouse I figured out the problem. Plastics sticking out of the top of my mouse which were supposed to be holding wheel ends, were actually displaced, and so my wheel was dancing between the clicking plastic mechanism. I just had to put it in the right place and problem was gone. My scroll is no longer jumping inside back and forth. Both ends are placed in those plastic holdings, so everything works fine. Sep 20 '15 at 21:38
  • Worked like a charm! Thanks alot.
    – Denn
    May 24 at 10:59

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