I suspect the mouse. Here are some of my recommendations:
1. Try with a different mouse. (Recommended for first solution).
2. If you updated the mouse software (Logitech), uninstall it.
3. I would suggest a script solution but if it's happening with explorer too, this wouldn't be the case.
4. If you use a tablet\pen, remove it and try.
5. Restore the computer to a date before this started happening.
6. If you have a scroll-wheel mouse, some of them have the ability to auto-scroll if you push down the scroll wheel, then release it. After pressing the scroll wheel, it will scroll up or down when you move the mouse up or down. To stop this action, simply press the scroll wheel on the mouse down, then release it. It might also be set...