I had noticed that looking at a single post, e.g. http://laymusic.org/wordpress/?p=267 didn’t have the navigation sidebar, and had vaguely thought that might be a problem. But then I started using an RSS aggregator (Google Reader) and realized that everybody who gets to a post that way is seeing the single post layout.
So I edited the single post Presentation file so that it included the sidebar. This reminds me yet again why wordpress is so popular — the PHP in the Presentation files for the default style is really pretty easy to read and modify, even though I’m not a very experienced PHP programmer.
LayMusic.org 