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I am running Windows 7 Home Premium x64, Service Pack 1.

My mouse is a Logitech MX620 Cordless Laser Mouse, driver provided by Logitech: Logitech HID-compliant Cordless Mouse, version (8/24/2010). SetPoint control center is version 6.20.60, driver version 5.20.51.

Now that the technical details are out of the way, here is my story: my computer came with Vista x86, and everything worked fine. I bought the OEM Windows install listed above and did a fresh install on a blank hard drive (i.e. not an upgrade.)

Now my mouse wheel is acting wonky. It scrolls just fine for the most part, but is super-sensitive when it comes to scrolling a tiny fraction, such as when I press it to use it as a middle button. Same hardware as with Vista, but obviously different OS and drivers (using x64 SetPoint and drivers, updated versions).

Again, it scrolls normally, it is just super-sensitive when moving it a tiny bit. If I go to middle-click to open a link in a new tab, the mouse will scroll the link out from underneath my cursor. If I scroll to the top of a page to click a navigation link, it might scroll back down one unit.

When I google or search StackExchange for help, everything comes up with "my mouse doesn't scroll" or "it scrolls too little/too far." My problem is it scrolls fine for normal scrolling, but if I touch the wheel a tiny bit, it will scroll when I don't think it should (and it didn't under Vista).

One other note -- I do have a "microgear" switch under the mouse that makes it "click" when I scroll, but that doesn't affect my problem. The amount of the wheel movement that is undesired is under the "gear threshold" or whatever of the mouse.

Essentially, I want to have a threshold where if I move the mouse wheel less than that amount, it does nothing. This is apparently how Vista handled it, but Windows 7 does not.

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up vote 1 down vote accepted

I had the same issue with my mouse (also with a button to toggle spin/ratchet mode). In my case, it was the mechanism that handled the ratchet mode wearing out. I was able to fix it a few times by taking apart the mouse and fiddling with the wheel. Eventually I had to buy a new mouse.

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I thought about trying to take it apart, but it has no screws that I can see. It appears that it clicked together and won't come back apart. But it worked fine in Vista, and in a single day didn't work fine in Win7. That smells strongly of some OS-level difference, I just don't know what. – Snowman Apr 13 '11 at 1:58
Sorry about the late response: turns out that buying a new mouse fixed it. Must have been one incredible coincidence that the mouse started going senile at the same time I installed Windows 7. – Snowman Nov 12 '11 at 5:26

For the record: I also have an MX620 and experienced the same issue in my win7 setup. It is not a hardware issue. You can verify this by terminating the SetPoint software (Right-click tray icon -> Exit) which will disable all tweaks.

For most applications, disabling "Smooth Scrolling" in the setpoint config is the solution. I also uninstall any browser extension added by the setpoint installer.

However, I have the impression that Logitech added some program specific tweaks for Microsoft Office, Adobe reader and the like. From time to time I stumble upon a program where the extreme sensitivity is back and even moving the mouse triggers the scroll wheel. As you say, switching the microgear has no effect on this over-sensitivity.

In any case, upgrade your drivers regularly, as Logitech Support often suggests this as the solution for scroll related issues:

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In my case it was the hardware, and swapping hardware confirmed. New mouse, no problem. Same mouse different computer, same problem. In the past two years I have been using a different mouse without the problem in my original question. Your answer may be appropriate for some who google this question, but in my case, it really was hardware. – Snowman Dec 14 '13 at 5:09

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