Fatal Error Due to Taxonomy and Forum Modules

I'm still getting this error and when I google "Fatal error: Call to undefined function taxonomy_vocabulary_load()," it appears others are getting an error in the forums module as well.

Someone, anyone, please help.

function forum_nodeapi(&$node, $op, $teaser, $page) {
  // We are going to return if $node->type is not one of the node
  // types assigned to the forum vocabulary.  If forum_nav_vocabulary
  // is undefined or the vocabulary does not exist, it clearly cannot
  // be assigned to $node->type, so return to avoid E_ALL warnings.
  $vid = variable_get('forum_nav_vocabulary', '');
 LINE 175 ===== $vocabulary = taxonomy_vocabulary_load($vid);
  if (empty($vocabulary)) {
    return;
  }

Thanks

i figured it out. i had put some data in the .htaccess file that related to the boost module and after disabling boost, i forgot to update .htaccess.