Index: branches/unlabeled/unlabeled-1.13.2/kernel/units/general/main_event_handler.php
===================================================================
diff -u -r5718 -r5905
--- branches/unlabeled/unlabeled-1.13.2/kernel/units/general/main_event_handler.php	(.../main_event_handler.php)	(revision 5718)
+++ branches/unlabeled/unlabeled-1.13.2/kernel/units/general/main_event_handler.php	(.../main_event_handler.php)	(revision 5905)
@@ -55,7 +55,7 @@
 
 			$ret = '';
 			$default_language_id = $this->Application->GetDefaultLanguageId();
-			if( $processed_params['m_lang'] != $default_language_id )
+			if( $processed_params['m_lang'] && ($processed_params['m_lang'] != $default_language_id) )
 			{
 				$language_name = $this->Application->getCache('language_names', $processed_params['m_lang']);
 				if ($language_name === false) {
@@ -69,7 +69,7 @@
 			}
 
 			$default_theme_id = $this->Application->GetDefaultThemeId();
-			if( $processed_params['m_theme'] != $default_theme_id )
+			if( $processed_params['m_theme'] && ($processed_params['m_theme'] != $default_theme_id) )
 			{
 				$theme_name = $this->Application->getCache('theme_names', $processed_params['m_theme']);
 				if ($theme_name === false) {