Ever since I updated to the newest 5.1.1, my top left of my screen has become a dead spot. I noticed this with my wifi. I can not click on the icon, but I can touch the word wifi and it will work. It also is unresponsive a several games and on the browser. If I click something that is tgere, I get no response. I did a factory reset after the update. Not sure what is causing this. I got the phone this June.