Index: sites/all/modules/event/event.module
===================================================================
--- sites/all/modules/event/event.module	(révision 1775)
+++ sites/all/modules/event/event.module	(copie de travail)
@@ -273,7 +273,7 @@
       // Lookup TZ ID based on TZ offset
       $timezone_id = event_timezone_map($user->timezone);
       // Update all users with the same offset.
-      db_query('UPDATE {users} SET timezone_id = %d WHERE timezone = %d AND timezone_id = 0', $timezone_id, $user->timezone);
+      db_query("UPDATE {users} SET timezone_id = %d WHERE timezone = '%d' AND timezone_id = 0", $timezone_id, $user->timezone);
     }
   }
 }