I seemed to have a rootkit which was causing startup to go directly into BIOS and give me a pop-up that used poor English and flawed grammar, informing me that 'something intruded' and asking me to click on OK.
I didn't click on 'OK', I hit 'reset' button, which rebooted successfully to Desktop.
Every so often, the weird BIOS pop-up would reappear, and 'reset' got me past it.
I have [FoolishIT], which I'm guessing was partially blocking a full-blown rootkit takeover.
So I did a backup restore of my entire OS from an older backup HD which was saved about April 2015.
Among a plethora of other actions, I ditched free AVG and updated Norton 360 Premier (which was never uninstalled from the backup), and I reinstalled Malwarebytes, which used to delay all folder & file openings for 10 to 20 seconds, and the MWB-related folder & file opening delays are gone.
A MWB scan found 6 threats and killed them.
I also ran updates and scans with Adwcleaner (which killed a few baddies), Desinstaller, and JRT.exe.
Then I spent a couple hours searching for vital up-to-date files on the goofed up HD that needed to be copied to the backup outdated HD.
Then I ran Glary reg-check, then CCleaner cleaner & reg-check, then ChkDskAssist on the backup HD.
Finally, I ran a [EaseUS Todo Backup Free 4.0] clone HD restore from the good but outdated HD to the goofed up-to-date HD.
AFAICT, all threats are gone, everything is up-to-date on both HDs, the backup HD is updated & disconnected again for 'the next time', and everything seems to be running smoothly.
On top of all this, I also discovered my vintage TOR Vidalia works fine now.