fixes issue #125

library/Zend/Cache/Frontend/Class.php

@@ -216,7 +216,8 @@ class Zend_Cache_Frontend_Class extends Zend_Cache_Core
         }
 
         $id = $this->_makeId($name, $parameters);
-        if ( ($rs = $this->load($id)) && isset($rs[0], $rs[1]) ) {
+        if ( ($rs = $this->load($id)) && (array_key_exists(0, $rs)) 
+                                      && (array_key_exists(1, $rs)) ) {
             // A cache is available
             $output = $rs[0];
             $return = $rs[1];