Index: includes/cache.inc
===================================================================
--- includes/cache.inc	(revision 7033)
+++ includes/cache.inc	(working copy)
@@ -34,7 +34,7 @@
     // cache timer. The cache variable is loaded into the $user object by
     // sess_read() in session.inc.
     else {
-      if ($user->cache > $cache->created) {
+      if (isset($user->cache) && ($user->cache > $cache->created)) {
         // This cache data is too old and thus not valid for us, ignore it.
         return 0;
       }