I have an optical mouse which has given me a lot of grief recently. I can move the mouse pointer properly but when I want to open a particular folder/file and click on it just once, it opens up several copies of the same file/folder. I have tried to reduce the speed of the mouse control and now it is at the slowest as per the settings menu, but even then a single click gives a “number of responses”, like I have commanded to open it several times. HELLLLP!
You could see if the problem is with the left mouse button by right-clicking on the file or folder.
You could see if the mouse is the problem by trying another mouse.
Mouse buttons often start to multi-click when they are worn out. In my case, it happens after a couple of years of heavy use.