Unexplained hard disk activity slowing PC to snail's pace

W10 Tweaker said:

That may be, however; all PCs are unique and there's constant requirement to uninstall many third party antivirus apps to restore normal Windows operation.

Norton & Avast are most commonly the problem regardless of any performance tests using another type of PC.

We're trying to correct the OP'ers PC, not debate what software is better.

I was merely responding to your unsupported affirmations about av products, which you've just done again.

But as dalchina has just stated, it's all guesswork, so I will leave him and other experts to hopefully sort out the OP's problem.

Gentlemen (or ladies!), forgive the delay in reply to your helpful messages. You need to be aware that I'm a daily PC user but what happens 'under the lid' is beyond my comprehension, as is driving a car. I know when things are functioning as I expect and I can tell when under-performance is occurring, but that's just about the limit of my capability. That said, I will do my best to take up the suggestions you've given me, but time is in rather short supply right now so there may be a few days' delay. But I haven't forgotten!