Why is my mouse acting erratically?
Users who have an optical mechanical mouse (most common mouse for desktop computers) are likely experiencing erratic behaviour because the mouse is not clean or is dirty. If you’ve cleaned the mouse and continue to encounter issues and this mouse has worked in the past fine unfortunately your mouse is likely defective. One additional test that can be done to help determine if this is the case or not is to connect the mouse to another computer. Otherwise we suggest replacing the mouse.
If you mouse is a cordless mouse then perhaps change the batteries or move the wireless receiver to a USB port on the computer that is closer to where you use your mouse.