It's been 4 years since I bought my Dell Inspiron 15 - 3543. I haven't faced any problem till date. But since a past few days, my touchpad or keyboard is not functioning properly. 

When I am scrolling down any webpage or any pdf, it suddenly goes to the top of the page or pdf and is getting struck there. I should press any keyboard key to restore it normally . Again after few seconds the same thing is repeating. It is really frustrating me a lot. 

When I play some video, it suddenly goes to the beginning of video and getting struck there without me touching anything. Suddenly, cursor is going here and there and some keys are randomly getting pressed. It is really irritating.

I have installed latest drivers for these but there is no change in the problem. 

Someone please help me with this. Why is it happening? Is there any problem with my hardware (touchpad or keyboard) ? Should I replace them ? Or what else could the problem be?