At my other address now. Quickly checked the unrecognised files. There were less than I'd expected, but I sorted them anyway. And surprise surprise, cmdagent has given up on its five minute frenzy and behaves impeccably again
Problem solved.
Mouse, I said it on a previous occasion and I'll say it again. You really are the cat's whiskers. Thanks for the help.
John
No problem John, glad to be of help

Best wishes
Mouse
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I'm locking this now as most of these problems appear to be resolved or work-arounds found. It will therefore probably be more useful to treat an remaining problems individually.
This FAQ
here summarizes solutions and work-arounds.
If you have a cmdagent related CPU trace please open a new topic, with the specific symptoms summarised in the title.
If you feel there is a strong case for unlocking this topic please PM a mod.
Best wishes
Mouse