Orphaned nodes after generating / deleting generated content ("n/a" appearing on pages)

Unfortunately I don't remember the exact sequence of events, but it involved creating content, comments, taxonomies and users [a few times each, with delete existing xxx checked]. Eventually it seemed nodes were orphaned. They wouldn't show up in the administer content page -- but I would get about 20 "n/a" occurrences on my home page, with tags in the html about being unpublished.

After deleting rows in the db from the relevant node* tables it resolved the issue. Not sure exactly how safe that was, but live and learn!

Those tables would be: node, node_revisions, node_comment_statistics, node_counter [I think] -- and the comments table.