Help setting up dual monitor screens (White rectangle box?)

I set up my dual monitors and so far loving it. Only problem is setting up wallpapers and this white rectangle in the top right hand corner of my monitor (The second monitor I hooked up) I can't right click on it or anything and when I restart the computer when it powers down the white rectangle goes away (So the monitor can't be damaged or anything right?)

I attached a image its really small I didn't want to send a large file so bare with me just open it with paint and zoom in any help will be appreciated.
Thanks

Any updates on this?

I am also having the same issue. A white box appears in the top left corner of screen.

It originally only appeared after the laptop had been to sleep, but now it can appear anytime.

If i click on the 'show the desktop' shortcut (far right of start bar), the white box will minimise.

I have attached a screenshot also.

Thanks
BD