I'll do my best to explain this but its weird to say the least.
So the two default themes (twenty ten and twenty eleven) appear under the Appearance>Themes tab in the wp admin.
However, if I add one new theme to wp-content/themes (even if its just an empty folder) all of the themes fail to show up on the Appearance>themes tab, except for the theme currently in use.
Anyone have any ideas?
--This is on a LAMP server (Ubuntu 12.04).