I have been a dunce - there IS a difference between this system and the old one…
Cleanup refused point-blank to work at all on my XP system, where N5 was officially “unsupported” from memory, and that system had N3, N4 and Uncle Tom Cobley & all installed on it.
My new W7 setup has never gone below N5 - I wonder if this makes the difference?
It shouldn’t, of course, but maybe it does?