My phone does this as well, but I've not replaced anything in it. My phone has operated perfect for the entire 24 months since I got it off my launch day order. I'm going to try a battery first in case it is somehow causing this. My battery is discharging at an accelerated pace these days and sometimes it charges extra slowly too. Also, my phone acts normal for about the first 10 minutes of usage each day and then after extended periods of non-use throughout the day as well. As for my screen, it acts like an ESD issue. I'll even see red and blue grid lines on the screen when it starts acting up. I hit the power button then immediately hit the home button and swipe it open. It will then give me about 10 seconds of regular usage before it acts crazy again. I've already bought a new phone as I can't go without, but I hope to get this one fixed and hang on to it as well.