In a fresh install of geeklog 1.8.1, changing the theme does nothing. It just always uses the default professional. Everything else seems to work fine, and the install went without any issues.
There's nothing odd at all in the logs (neither geeklog's nor apache's).
Any suggestions?
Btw, renaming a theme's directory to "professional" works, so at least we know..er....that.

There are two options for the theme: The one in the Configuration is the site wide default (for new and anonymous users) but can be overridden by the option under My Account. So make sure to change that option as well.

bye, Dirk