I found the way to fix this url issue : actually it was just an accent reason !!! i went to seetings->forums .. in there go to the bottom at “custom endings of URL of the profil user page” and just make sure, in the form fields, that u dont use any accent like in french (my current language!) : example for topics created fill it with sujet “demarre” (not démarré) .
hope it will help others 😉