I’m not sure either.

So in fact I have done what you suggested in your most recent post but it still led to my reinstall not being right.
Are there any error messages, can you give us any more information?

However, I would guess because you have installed avast in a non-standard folder, awsclear.exe and RejZor’s External Control Tool may have difficulty not finding the avast installation where expected, especially if avast has been partially uninstalled so the uninstall information is not available,so defaults may be used (incorrectly in this case).

This may well be the reason files were left behind as you mentioned, though I can’t say for certain.

I have not installed to the default which I recall is "C:\Program Files\Alwil Software\Avast". And I prefer not to do so as I do not remember supplier's names as well as I remember their software's name.
This could be a contributory factor, there could possibly be multiple registry entries for avast.

I too am running out of ideas, but running a registry cleaner looking for registry keys that have bad/missing links may get rid of any invalid avast registry entries.