Thank you for your suggestion. I appreciate you wish to help me to repair my Windows installation.
But - and it is a big 'but' - it was a Windows upgrade, the autumn creators' update, that broke Task Manager on my PC in the first place.
Task Manager did not conflict with anything on my PC until the autumn update. Since then, it conflicts with two major browsers ... though not Edge, funnily enough.
I would add that when the problem first manifested on installing the autumn update, I rolled back to the previous Win 10 build, which cured it. Reinstalling the update brought an immediate recurrence.
While I accept that this issue doesn't affect all machines, and that it may well be caused by legacy conflicts in my Win 10 installation (although SCANNOW finds no missing or corrupt files), my PC is my livelihood.
I'm sure you'll understand why I'm not willing to lose more business hours carrying out an in-place upgrade to cure the last update, especially as that route clearly carries its own significant risk of causing further disruption when one reads users' comments on the thread you linked to.
It's far more practical for me simply to accept that the autumn update broke Task Manager as far as my PC is concerned; disable TM and use a third party alternative.