If the mouse has a ball, you might remove it and check to see if fuzz has built up on the rollers.

You might also download AND install malwarebytes from http://fileforum.betanews.com/download/Malwarebytes-AntiMalware/1186760019/1

First download, then install, then update, then run complete scan, then fix all it shows.

These are the first two things I'd try.

If the problems are relatively recent you might even try to restore the computer to an earlier date.  Click on start icon at lower left, type restore, then click on the place I've pointed to.  Pick a date prior to the problems.

(restore.JPG)

restore.JPG (24KB - 89 downloads)