Right on both counts. With added, the menu looks right and the page validates on the "bad" pages, but will not validate on all the other pages (although it doesn't affect the appearance, at least not in FF).
I think at least for now I'll use a special "Bad Menu" template for pages with the problem. It's not pretty on the backend, but at least the site users will see neatness.

Thanks for all your help guys.
-- Genevieve