=== modified file 'modules/block/block.module'
--- modules/block/block.module	2007-11-06 11:40:15 +0000
+++ modules/block/block.module	2007-11-07 20:19:41 +0000
@@ -240,6 +240,9 @@ function _block_rehash() {
           $block['module'] = $module;
           $block['delta']  = $delta;
           $block['theme']  = $theme_key;
+          if (!isset($block['pages'])) {
+            $block['pages'] = '';
+          }
           // Add defaults and save it into the database.
           drupal_write_record('blocks', $block);
           $blocks[] = $block;