been fixed yet though, but at least it won't try to load non-existing
  themes.  That is, you might not be able to select your prefered theme,
  but you should be able to surf the pages with the default theme no
  matter what.  Hence, it semi-fixes the theme problem reported earlier
  by UnConeD.

  Natrak: make sure the new user system won't suffer the same problem.
          Use file_exists(string filename) to check whether the theme
          does actually exist.  If not, load the default theme.