Check the contentstructuremenu.ini file for your administration interface's siteaccess. Basically, all the classes that you want in the content structure menu must be declared, including the root node (if you have swapped the folder).
Here's some details: http://ez.no/doc/ez_publish/technical_manual/4_0/reference/configuration_files/contentstructuremenu_ini/treemenu/showclasses
<i>> Your serveur is config with CGI/FastCGI. > Try to desactivate treemenu with this option in contentstructuremenu.ini</i>
You mean PHP in the CGI mode? How does that affect a feature that I though to be a browser-dependent? I have many CGI installations, never had a problem with the contentstructuremenu...