--- C:/Users/MartinL/Downloads/xampp/htdocs/www/sites/all/modules/duration/duration.module.orig	Mon Feb 01 11:29:23 2010
+++ C:/Users/MartinL/Downloads/xampp/htdocs/www/sites/all/modules/duration/duration.module	Mon Oct 11 14:31:51 2010
@@ -85,7 +85,7 @@
  * Implementation of hook_content_is_empty().
  */
 function duration_content_is_empty($item, $field) {
-  if (empty($item['iso8601'])) {
+  if (empty($item['iso8601']) || $item['iso8601'] == 'PT0S' || $item['approx_seconds'] == 0) {
     return TRUE;
   }
   return FALSE;
@@ -139,6 +139,9 @@
   if (isset($element['#node']->duration)) { // loaded by duration_handler_field
     $element['#item']['duration'] = $element['#node']->duration;
   }
+  if (duration_content_is_empty($element['#item'], NULL)) {
+    return '';
+  }
   return duration_format_list($element['#item']['duration']);
 }
 
@@ -149,6 +152,9 @@
   if (isset($element['#node']->duration)) { // loaded by duration_handler_field
     $element['#item']['duration'] = $element['#node']->duration;
   }
+  if (duration_content_is_empty($element['#item'], NULL)) {
+    return '';
+  }
   return duration_format_hms($element['#item']['duration']);
 }
 
@@ -158,6 +164,9 @@
 function theme_duration_formatter_colons($element) {
   if (isset($element['#node']->duration)) { // loaded by duration_handler_field
     $element['#item']['duration'] = $element['#node']->duration;
+  }
+  if (duration_content_is_empty($element['#item'], NULL)) {
+    return '';
   }
   return duration_format_custom($element['#item']['duration'], '%h:%M:%S');
 }