Bingo! You are the man ... !! Common Dialog Boxes - Enable or Disable Dropdown List of Recent Files
was the solution.
I have been coming to terms with Windows 7 (after WinXP) -- security, Admin and owner -- are all new to me.
I have applied changes (manually) in the Windows 7 Registry, as owner.
Should I instead apply it as administrator, and what hive-path would that be?
Thanks again for your help