Hello again all, and thank you for the advice so far.
To follow up, I have tried Nergal, Hazelnut and Trium's suggestions.
I have downloaded the portable tweaking.com program and run 01) Reset Registry Permissions, 02) Reset File Permissions, 05) Repair WMI and 33)Repair Performance Counters.
The above were performed while in safe mode after a registry backup and system restore point taken beforehand.
Complements to the software author. It looks to be a very useful utility. ( I also like the fact that it is a portable program).
CCleaner v5.10.5373 reports no system restore points.
CCleaner Portable v5.10.53.73 reports no system restore points.
System Restore reports that there are 20 (twenty) system restore points.
There are no ERRORS in the event viewer.
I have run both the installed and the portable versions of the CCleaner program with the /debug flag. The pertainent parts of the log do not differ from those indicated in my previous post.
I have NOT tried to restore one of the restore points that System Restore reports, although I have done this many times in the past with no problems. (I don't particularly want to do this right now for obvious reasons, everything else seems to be working fine)
I would be interested in why Trium suggests trying the Windows defragmenter, that is what difference would be expected? As far as I know the [competition] defragmenter uses the Windows API, and I have been using it for some years now without problem, including the currently installed version.
Once again, thankyou in anticipation of any replies, and any further suggestions would be gratefully received.
Kindest Regards.