In some cases that happened when typing consciously and you are about to finish your text that you typing but while typing your palm accidentally touches the touchpad. It is because the touchpad is so sensitive. After years of years, it gives a huge pain while at work. It rests your palm to control the mouse with only fingers instead of hold whole by hand. Touchpad gives instant mouse control at the same place while typing. It is also important that you make sure to sit with the correct posture where you try to use your touchpad and keyboard from the correct angle which puts less stress on your arms or wrists and to get rid of this situation. But suddenly your mouse moves on other sides and clicked at the wrong place, it happens when you are using the external mouse on the laptop. It happens to some of the users when you writing an important email, do excel work or other work.
