Have you tried reinstalling/updating the mouse driver?
Click on the START button on the desktop, type "device manager", when you see it in the menu, click on it once... When device manager opens, look where it says, "mice and other pointing devices". Click on the "+" sign next to that, right-click on the mouse in the submenu, click "uninstall" and restart the computer... Test out the mouse, and if the problem remains, go back into device manager and click on the "update" option instead of the uninstall option... If there is a better driver than the one you have, M$ will install it... If there isn't you'll continue to use the same driver you have now...
what is the make/model of the mouse? Sometimes M$ update isn't reliable... You may be able to find a better driver for it from the manufacturer website..