WordPress Upgrade Problem

Hi,

I upgraded from wp 3.0 to wp 3.01 and i had this problem in the admin section:

Fatal error: Call to a member function add_rewrite_tag() on a non-object in /mounted-storage/home119c/sub009/sc18587-YDFT/www/wp-includes/taxonomy.php on line 289

do you know why, and how to solve it?…

Thanks