Index: wp-admin/includes/template.php
===================================================================
--- wp-admin/includes/template.php	(revision 17913)
+++ wp-admin/includes/template.php	(working copy)
@@ -331,10 +331,12 @@
 		return;
 	}
 
-	if ( $mode == 'single' ) {
-		$wp_list_table = _get_list_table('WP_Post_Comments_List_Table');
-	} else {
-		$wp_list_table = _get_list_table('WP_Comments_List_Table');
+	if ( ! ( is_object( $wp_list_table ) && is_a( $wp_list_table, 'WP_Comments_List_Table' ) ) ) {
+		if ( $mode == 'single' ) {
+			$wp_list_table = _get_list_table('WP_Post_Comments_List_Table');
+		} else {
+			$wp_list_table = _get_list_table('WP_Comments_List_Table');
+		}
 	}
 
 ?>
@@ -1742,7 +1744,7 @@
 
 	if ( !empty($wp_current_screen_options) )
 		$show_screen = true;
-		
+
 	$show_screen = apply_filters('screen_options_show_screen', $show_screen, $screen);
 
 ?>