Thanks for helping me with my hard drive - fortunately I solved the problem!
But I have got another thing to consider - it is Firefox scrolling performance.
I normaly use Chrome but as I used to use Firefox few years ago I just wanted to go back to it. So... installed it, started to browse. Found scrolling terrible glitchy. Before I bother you guys I did some research about. There is no much info on this: I tried to uninstall all addons, switch on and off smooth scrolling etc. and nothing worked.
I really want to utilize the browser but this glitch makes me thinking bad about it.
Is there any way to fix it?