i was using version 2.8 for a month now. Today i logged in as admin to edit some content. After login i noticed that there was an update for WP and decided to use the auto update. After the update was finished i was not able to see my blog or enter the config page as admin.
Every time i try to login or view i get the following error:
Fatal error: Call to undefined function is_admin()in ...wp-includes/vars.php on line 16.
Is there someone who can tell me what to do to fix this?