I have installed elementary OS 0.3.1. I notice that I need to press my mouse buttons very hard to make it work. I can move the cursors around the screen smoothly with no problems, but the main problem are the buttons. Somtimes it even happens that the buttons do not work at all. I can move my cursor, use my keyboard, but I can't click on anything no matter how hard I press. It is not a hardware problem, because it didn't happen in Ubuntu or Fedora or Windows. I even tried two different mouses, plugging them in two different ports without any result. How to solve this?