Last month I updated my Windows 7 Desktop to Windows 10. Until yesterday, I had no difficulty with Firefox. Was searching a topic (don't remember it now) and opened a bad page. No warnings, just instantly this note taking over my screen: "System Alert. Your computer is infected with an adware or malware causing you to see this popup...." the message insisted that I call a number immediately and not restart my machine to avoid data loss. I recognized it as a lie, but was unable to close any pages. Each attempt merely opened another of the same. Killed the page with Task Manager and uninstalled Firefox (the other browsers were not affected) and reinstalled. Still there. 2nd uninstall I deleted the folder Mozilla Firefox from my C drive and restarted the machine. Reinstalled Firefox. Still there. 3rd uninstall I deleted the folders Mozilla firefox and Mozilla Update Service and Mozilla Thunderbird and restarted. downloaded the installer again (not to use the same previous download). When I reinstall, the fake warnings are immediately present and they are open on more tabs each time. Windows Defender quarantined and eliminated it once. I'm trying again. Haven't reinstalled yet. Currently my machine only has Edge and Chrome (neither is affected). Really want to have Firefox back. Any additional tips?