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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?

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Are you scrolling with a scroll wheel, or by grabbing and dragging the scroll bars? – Ƭᴇcʜιᴇ007 Jun 17 '11 at 0:19
    
With mouse wheel. Tried different mouse, and no problems. – bnieland Jun 23 '11 at 15:15
    
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. – Jesse Slicer 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
up vote 3 down vote accepted

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

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

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.

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1  
@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
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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. – Consider Me Sep 20 '15 at 21:38

Dust. No, really. Dust inside the mouse. Open it and clean the wheel. Or buy a new one, they are so cheap.

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Not if you're using an ergonomic mouse – autonomatt Jan 7 '15 at 16:35

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