Blank box on laptop screen

[topsi]

I have a blank box at the bottom right hand corner of my screen, it just appeared as if by magic. It is white at the top and blue at the bottom. It is getting in the way!
How do I get rid of it. is it a sign that my computer is on its way out?

What Operating System are you using? Windows? If so where exactly is this box appearing? On the Start Bar next to the clock?

Does a reboot make it go away?