A sort of a postscript:
Having tried all your welcome suggestions to rid my machine of of this errant Microsoft Word zero k file, I've returned it to the Incompatible Software folder where it's out of sight and not causing any harm (well maybe). I've applied the Combo update and all is otherwise well.
However Disk First Aid, invoked from any source, still fails and tells me there is "corruption" that needs to be repaired and I'm hoping that this is not a sign of impending hardware doom. Because I've used it for years, probably needlessly, I'm waiting for Diskwarrior to become APFS compliant and hoping it does so very soon. Lot of hope here.
cheers all
Andy
