Oh, that's the charmbar/searchbar/wifi-internet bar thing. Yeah that is unavoidable. That's why I try to recommend replacement programs so you dont use that. Just avoid clicking on the corners of the screen, or do this in classic shell... That should help avoiding that. EDIT: also, if the black bar appears and you don't want to restart to fix it, restart explorer. (open task manager, right click Windows Explorer, press Restart).