There is a popup that appears on the screen that can't be selected

Question

There is a some sort of of popup that appears in the middle of the screen and stays there. It covers the logon screen and occupies the center center of the screen. It randomly disappears but returns a few minutes later. I cannot be selected from alt-tab or the mouse. I can't identify the name of it to kill it in task manager.

I'm attaching a shot of this (I had to take a pic with my phone). Does anyone know what this is or how to get rid of it?

Thanks.