I have an optical mouse that has been working fine. Just the last couple of days it acts up. When scrolling down using the center button (not wheel) it will automatically scroll back up. I started using the click and drag on the right of the screen and when I lifted my finger from the left button it would scroll back up. Now I can sontinue to hold the left button down and it still scrolls back up. What is going on? Any help would be appreciated.