Index: modules/block/block.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/block/block.module,v
retrieving revision 1.354
diff -u -p -r1.354 block.module
--- modules/block/block.module	4 Aug 2009 06:38:56 -0000	1.354
+++ modules/block/block.module	6 Aug 2009 11:30:29 -0000
@@ -237,7 +237,6 @@ function block_page_alter($page) {
 
   // Populate all block regions
   $all_regions = system_region_list($theme);
-  $visible_regions = system_region_list($theme, REGIONS_VISIBLE);
 
   // Load all region content assigned via blocks.
   foreach (array_keys($all_regions) as $region) {
@@ -250,7 +249,7 @@ function block_page_alter($page) {
 
       // Append region description if we are rendering the block admin page.
       $item = menu_get_item();
-      if ($item['path'] == 'admin/structure/block' && isset($visible_regions[$region])) {
+      if ($item['path'] == 'admin/structure/block' && $visible_regions = system_region_list($theme, REGIONS_VISIBLE) && isset($visible_regions[$region])) {
         $description = '<div class="block-region">' . $all_regions[$region] . '</div>';
         $page[$region]['block_description'] = array(
           '#markup' => $description,