Warning: require_once(./includes/form.inc): failed to open stream: No such file or directory in /usr/local/www/drupal6/includes/common.inc on line 2733

Fatal error: require_once(): Failed opening required './includes/form.inc' (include_path='.:/usr/local/share/pear:/usr/local/www/Libraries') in /usr/local/www/drupal6/includes/common.inc on line 2733