Tile menu of my Lumia 535 get stuck. What should I do?

[Indula]

I transferred some pdf files from a laptop to my lumia 535 ( bought about a week ago). The laptop was infected with many virus programs. After that my phone started to stuck when I tried to use the tile menu. Not only that onscreen keyboard also malfunctioned. when i touch one button for once, the phone recognize it as many times. I mean a letter I wanted to be typed once, typed many times. When I try to slide down the tile menu the application where my finger first touched opened without sliding it down. I did the slide downs correctly, but it keeps happening again and again. I did the soft reset and also hard reset using the phone reset, but it occurs again after a while. Please explain what should I do? Should I call for the warranty or is it a simple problem that I could correct myself.