Rectangle transparent shield has appeared blocking taps on keypad iPhone 5

A weird rectangular, transparent, shield has appeared "above"

any key selected from lock code to apps that

blocks any tapping on any keys or keypad.

If I tap hard and fast, it might catch but then enters the number,

or whatever, multiple times (cause of rapid tapping).

This has happened 6 times since March,

where I've had to fully restore factory setting.

First time, didn't know had to manually back up apps, dir., etc.,

so had to re-build it all 1st time.

Since, same weird transparent shield appears,

then no button will "select" or function until full restore.

Because after rapid tapping, hard, one might stick, after 1, 2, 3, Dozen

taps, it proves something transparent is blocking

(the rectangle appears as a fine point box line hovering above anything I tap).

This last time, the full restore put it back, and the problem is still there.

Am back on my old 4S, which I kept, as spare (amazingly) until a fix.

Will prolly have to send it in on a slow boat to China, where it

was made, which is gonna be quicker than a repair job, I'm sure.

Nothing like this comes up on the forum, any advice is well appreciated.

Thank you kindly.