What is this grey rectangle box on my laptop screen?

[Trevane]

Well today on my screen is a grey rectangle box that appeared randomly when I turned on the computer I can move it around and everything but I can't right click it or anything.

I have scanned my computer for a virus but nothing came up. The only thing I can say is that it is a letter on there maybe a 'c' or 'o' but it seems cut off so can't see it all

Anyone know what it is and how to get rid of it?

I would include an image so you can see it better but I have no idea how to add it from a saved file.

 

[C12Friedman]

Does your monitor support picture-in-picture? Is it enabled?

This guide explains how best to post pictures and even how to give your posts some "style" http://www.tomsguide.com/forum/id-2299665/read-forum-rules-styling-posts.html