I had a second computer that I decided to fix up. Installed a new hard drive and upgraded memory cards. It worked fantastically (considering my computer abilities which ain't much) for several hours and then all H broke loose. "Windows Security Renewals" came on and volunteered to fix everything for a small fee, of course.
Anybody heard of this scam?

Yes, Google it. If you decide to wipe the drive and rebuild, apply all critical Windows Updates once you can boot into Windows and before general web browsing. If you are running an older version of Windows, XP for instance, there are hundreds of patches needed to secure the machine. An unpatched system can be compromised pretty quickly just by general browsing and even faster if there isn't a router/firewall between the machine and the Internet.

You picked up a rogue, reboot into safe mode with networking, grab FREE version of this, update and run, yes it will install and run fine in safe mode with networking:
Malwarebytes : Free anti-malware download

Thanks but that was about 5 months ago and the patient has been buried.
I'll save the link in case it happens again.
Your assistance is appreciated.