fatal error on dismiss link Oo

hi !

Well new and strange...

Fatal error: Call to undefined function wp_get_current_user() in /home/carnets/public_html/wp-includes/capabilities.php on line 1028

on clicing on the dismiss link !

http://hippocampe.passion-cheval.net/wp-admin/network/update-core.php?page=wpmudev&dismiss-release=231

wp 3.1.2 U N last version