Since the most recent big update to Windows 10, my PC is barely usable. Edge occasionally will not run at all (nothing happens when I click its icon on the taskbar or from the Start menu); when it does occasionally respond, the icon on the toolbar is flashing away and the shadow effect on the browser window itself is also flashing. When I go to shutdown, the 3 options only flash up for a fraction of a second (shutdown, restart or sleep) and it's a race to try to mouseclick in time to select one of them. The PC is an old HP desktop (about 2009 IIRC) that originally ran Vista, then Win 7 and then Win10 perfectly OK until the last update. 3GB RAM, 2.2GHz processor, plenty of free hard drive space. Any suggestions on how to fix?