This just suddenly started a couple days ago. These things can pop up at any time, and can disrupt me being able to do things on the phone since they take up most, or all of the screen. I am unaware of any apps I have added, and cannot identify anything specifically likely to be at fault in my list of apps. This is driving me crazy. It's not possible, at this time, to do a factory reset on the phone. What is causing this, and how do I stop it? 

Thanks for any assistance.