Well, maybe not - but it felt like it.
Friday morning I started my PC as usual, except I got an error message from SDtray.exe - that's the background scanner for Spybot. Having rebooted, it did it again. I searched the online forums which suggested solutions. After numerous attempts at clearing some files, then numerous attempts at clean installs - it wouldn't even install - I decided to give up. The log file was telling me the program was unable to access its own .tmp files.
I thought it may be either malware or a virus. Ran Kaspersky AV - nothing. Ran Malwarebytes - nothing.
So I decided to restore from backup (via Acronis) to a date when I knew it last worked ok. That was fine, the program was back working.
However, now my Nikon NX-D software had problems. Whenever I tried to change an image, the program crashed. As NX-D uses .tmp files, there was a pattern emerging. Even though I had restored from backup, something was still affecting access to .tmp files.
That was enough. I decided I was long overdue for a clean install of Windows. Using Windows USB install creation tool to create installation media, I did a clean install of Windows (10).
It was easy peasy and took only 30 minutes to get back up and running; this time with a fresh install of the latest version of Windows on a cleanly formatted disk. It took me the rest of the day to install all my other software but it was worth it. Everything is now fresh and speedy 