At first I thought it was a glitch , but just happened again. Had the S6 for about 5 days now. First time this happened on the second day, and again tonight. I will be in the Home screen and trying to do something, like click on anything or swipe and suddenly the screen will flash, from the window that was on, to the one I tried to use, back and forth, about every half a second. During that time no matter what I do , won't work, because it flashes back and forth. I tried to restart or shut off, but if I press on the on/off button the window to restart will pop up but before I can even push on any button, it has flashed back. I can't use phone or anything, sometimes if I catch it just right between 2 flashes I can open an app, but it just goes to the first window, flashing nonstop. By accident I found the ONE way to turn this off...when a call comes in it shows the call and stops flashing. If I hang up it continues to flash, but if I push the off button during the call it will let me restart and its back to normal. How severely frustrating !! During this flashing I can do NOTHING with the phone, not even turn it off ! Since there is no removable battery...I have only put a couple of Apps on the phone, weather, facebook, nothing "weird", nothing I haven't had on other phones. I have had my daughter make a video of what is happening, I will try to upload it. I suppose I will have to return this dang phone, right when I finally got it set up the way I like...big sigh.