=== modified file /modules/comment/comment.admin.inc ===
--- modules/comment/comment.admin.inc	2010-10-08 15:56:04.527213259 +0530
+++ modules/comment/comment.admin.inc	2010-10-08 15:57:18.199220880 +0530
@@ -130,6 +130,7 @@ function comment_admin_overview($form, &
     '#header' => $header,
     '#options' => $options,
     '#empty' => t('No comments available.'),
+    '#default_value' => array(),
   );
 
   $form['pager'] = array('#theme' => 'pager');