Fix: Touchpad left click will intermittently not work in Windows 8.1

If you have a laptop with a touchpad (trackpad) and you upgraded to Windows 8.1, you may have noticed that occasionally, the left click of the touchpad does not work. For example, it may not work at startup at all until you press some key on the keyboard after which it starts working. Or you may be unable to move the mouse pointer right after you type something. Sometimes, the left also won't work unexpectedly in games. Let's see how to fix.