When I'm on the dashboard / search page, etc, the link in the header don't work. But the links in the navigation tree work fine.

Here is what I see on the header links with FireBug :

"<a id="j_id16:j_id19:3:j_id21" class="OraLink" href="#" onclick="submitForm('j_id16',1,{source:'j_id16:j_id19:3:j_id21'});return false;" name="j_id16:j_id19:3:j_id21">Gestion des vocabulaires</a>"