A disturbing popup screen appears frequently - why?

[AC Question]

A small popup screen appears frequently. "Brightness" is written over it. It guards the main screen and quite a disturbing element.

I have hard reset the tab but that does not solve the problem.

is it a virus?

 

[B. Diddy]

Welcome to Android Central! Which tablet? Show us a screenshot: http://forums.androidcentral.com/am...ide-how-post-screenshots-android-central.html