Before I get into it, enjoy WTD#344. It’s sure to be a classic…

Success! It turned out to be a couple of things. The first was the presence of a weird .htaccess file that was preventing access to some key folders. The second was that the plugin I was using, WP-SimpleViewer, has some kind of conflict with a the newly added Simple Tags plugin. Whenever the latter was turned on, the former would cease to function.

In trying to fix the problem, I came across NEXTGEN Gallery. While that plugin is pretty new, it seems to work more or less as advertised, so it was a no-brainer to replace WP-SimpleViewer.