Hello, thank you for the reply!
I never made hardware changes as my PC was in service period and I paid in installments. I have two external HDs and 2 flash drives always attached to PC.
The software change I made was the upgrade from 8 to 8.1. I did some updates later. But I noticed when updates are turned on this causes my PC often not to start on boot. I turned off the automatic updates and started updating manually. Later while updating
manually the downloading froze almost every time and I gave up and probably didn't update from over an year and half.
I didn't check in IE because I totally avoid using it. I had redirecting issues and because of that I made Mozilla my main browser.
All browsers are up to date, set to automatic updates, excluding Mozilla because its latest updates had malware detection (I have 96 add-ons and most likely some of them might caused that). Mozilla plugins are up to date too, as well as Flash Player and
Java.
I dig deep in Mozilla knowledge base and did everything described. I also set custom size of cache. At first I thought it is only Mozilla issue and disabled some add-ons. But when checked in Opera, Opera beta and Chrome I faced same again.
Some'd say AVG Free is the problem because Link Checker, I disabled it yesterday but not much difference. People I know in real life keen to think AVG Free is heavy and might cause issues in general.
Do you think that non-updating OS may be the main problem?