How to remove translucent gray bar across world

Today while my daughter was playing Minecraft I noticed that there appeared to be a translucent gray bar covering most of the screen - everything except a margin at the top and bottom. It went away any time I went into the menus, and after fiddling around with the settings I couldn't get it to get away. I tried joining a second player and the bar got narrower, still covering the entire width of the screen but extending only a bit above the inventory bar to just past 1/3 of the screen up.

How can I get this bar to go away?

Update: I realized this bar looks like the gray bar that pops up whenever there is text - except taller. So I started spawning creepers until I couldn't any more, and sure enough, I did not get any messages telling me I was at the limit of how many I could spawn, even though I could no longer spawn more.

Update 2: I was able to make the problem go away as described in the answer below, but after restarting a second time, I am now stuck with the rotating progress "boxes" at the main menu; it has been sitting there for over ten minutes now not letting me do anything (except turn off the unit, which doesn't fix the problem, as soon as I try to start Minecraft again it gets stuck when I try to log in.)

I finally got the issue to do away. A simple restart of the game did not fix it, so I powered down the unit for about 15 minutes. Then after powering it back up, I loaded a different game, the exiting that and started Minecraft, and upon loading the same world the issue went away.

After this, I had additional problems which cycling power in this way did not fix. To completely fix the problem, I had to go to the home screen and find my way to restart the box from the menus (I think under settings, I will go back and look to confirm this as soon as I get the chance.) When I did this, instead of just the white logo on black screen I got the logo on the green background back that and it did a full restart. I then had to select a couple of time which save I wanted; there were two from the same day, and I picked the older one to sync to clear out any remaining bad data.