Volume control appears in middle of screen.

I Started having this problem about a month ago. Went to local Apple Store. Went through the reset step, no help. cleared out a lot of Apps I was not using. Backed up iPad on laptop and went back to store and they cleared it and reloaded IOS and when it restarted the box appeared immediately. They gave me options which consisted of a new iPad. Decided to wait a few days and check around. Shortly thereafter I discovered that by pressing in the middle of the volume control button on the side the box went away. I did not have to do a restart as I had been doing. Decided I could live with that for a while. I continued to do this for a few days and the time between incidents seemed to get longer. About 4 or 5 days ago was the last time the box appeared. Apparently the repeated pressing of the button has cleared some dirt or debris or fixed something someway. But give it a try, it's cheaper than buying new and faster than doing a restart. Good luck.