I have recently set up WordPress on an Ubuntu 6.06 server, and it works fine. The two default themes work fine, and the wp-content directory has uniform permissions. However, if I add a new theme, even by just copying the default folder to a new theme folder, it displays the theme but doesn't work. It displays no theme at all, just text. Again, the two defaults work, and I've checked and rechecked that the permissions and owner are correct and the same among the whole wp-content folder.