[bad_madman]

Strange. Which version of vB do you use? It seems to be an old version.
Replace the complete highlight-part by this code.

PHP Code:

// words to highlight from the search engine
$replacewords = array();
if (isset($highlight) && $highlight != '') {
  $highlight = urldecode($highlight);
  $highlightwords=explode(" ",str_replace("/","\/",quotemeta($highlight)));
  while (list($key,$val)=each($highlightwords)) {
    $val = strtolower($val);
    if ($val=='or' OR $val=='and' OR $val=='not') {
      continue;
    }
    if ($allowwildcards) {
      $val = str_replace("\*", "[a-zA-z]+", $val);
    }
    $replacewords[$key]="$val";
  }
} 


edit:
code changed