Hello there.
After upgrading from 2009-02-14 to 2009-12-25, the URL on the logo (top right on default template) added a trailing slash. Therefore, the URL changed from something like:
http://gsiwiki.estradas.pt/doku.php
to
http://gsiwiki.estradas.pt/doku.php/
This last URL gives an error of "file doesn't exist" referencing a "index.php". It works ok if I remove the trailing slash on the location bar of the browser.
It happens with all browsers I tested.