--- blocks404.module	2011-03-03 10:04:10.940063458 +0000
+++ blocks404.module.new	2011-03-03 09:47:54.018242240 +0000
@@ -43,7 +43,13 @@ function blocks404_404_page() {
  */
 function blocks404_preprocess_page(&$vars, $hook) {
   if (strpos(drupal_get_headers(), 'HTTP/1.1 404 Not Found') !== FALSE) {
-    module_load_include('inc', 'blocks404', 'blocks404.active');
+    $blocks404_file = drupal_get_path('module', 'blocks404') . '/blocks404.active.inc';
+    if (is_file($blocks404_file)) {
+      require_once($blocks404_file);
+    }
+    else {
+      return FALSE;
+    }
     _blocks404_preprocess_page($vars);
   }
 }