--- wp-includes/widgets-2.8.1.php	2009-07-10 15:12:26.000000000 +0200
+++ wp-includes/widgets.php	2009-07-18 16:08:56.000000000 +0200
@@ -933,9 +933,20 @@
  * @param mixed $index, sidebar name, id or number to check.
  * @return bool true if the sidebar is in use, false otherwise.
  */
 function is_active_sidebar( $index ) {
-	$index = ( is_int($index) ) ? "sidebar-$index" : sanitize_title($index);
+  global $wp_registered_sidebars;
+	if ( is_int($index) ) {
+		$index = "sidebar-$index";
+	} else {
+		$index = sanitize_title($index);
+		foreach ( (array) $wp_registered_sidebars as $key => $value ) {
+			if ( sanitize_title($value['name']) == $index ) {
+				$index = $key;
+				break;
+			}
+		}
+	}
 	$sidebars_widgets = wp_get_sidebars_widgets();
 	if ( isset($sidebars_widgets[$index]) && !empty($sidebars_widgets[$index]) )
 		return true;