Index: modules/block/block.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/block/block.module,v
retrieving revision 1.291
diff -u -p -r1.291 block.module
--- modules/block/block.module	16 Dec 2007 10:30:09 -0000	1.291
+++ modules/block/block.module	17 Dec 2007 15:33:37 -0000
@@ -459,6 +459,9 @@ function block_list($region) {
             // Check plain here to allow module generated titles to keep any markup.
             $block->subject = $block->title == '<none>' ? '' : check_plain($block->title);
           }
+          if (!isset($block->subject)) {
+            $block->subject = '';
+          }
           $blocks[$block->region]["{$block->module}_{$block->delta}"] = $block;
         }
       }