Since updating Windows a few days ago, I've noticed that there seems to be a regular pop-up window that looks like the old command-line box. It happens whether I have other programs open or not, and I see a quick outline of the window for a second or two, then it disappears. I've had Windows 10 for about a year, installed on a new laptop. I don't remember this window popping up like this before, only occasionally on start-up or shut-down. Is this something I need to be concerned about?