Why Samsung Galaxy Pocket screen is hard to swipe

Are you experiencing this problem?
Do you know why this is happening?

I've experienced this problem a day ago. Every time my phone sleeps and I need to unlock it, I'm having a hard time to find the right position on the screen and the exact pressure I need to give to swipe my finger on it.

I asked myself, what is the last thing I did on my phone before this problem exist? As I remember, I installed this kind of software. So, to fix it, I uninstalled that software. But the problem is still there.

The last option I made is to format my phone. 

To format your Samsung Galaxy Pocket, go to your Settings

then Privacy

Check the box to Format USB storage

 then tap Reset phone

tap the Factory data reset

then tap Erase everything

After that follow the next instructions you will encounter once your phone is already formatted.
Then your  Samsung Galaxy Pocket screen will now back to it's normal function.
I guess, my phone got a virus from anywhere else  that's why formatting it solves the problem.