I had a free avg version antivirus and I took it out thinking that it was the cause, but also with this antivirus I had the same problem
check in the task manager, there gives you an idea which application or hardware is consuming your RAM
I can not go to the Internet to put antivirus or ccleaner, since the inernet explorer does not go and I do not know how to enter the internet without this option
I could not also have to format it and I do not know what happened, but when it starts a few minutes left the black screen and then it is only with the wallpaper but nothing more neither icons nor start, nothing more than the background and so it remains, no change or go into error-proof that's why I think he died