Index: includes/bootstrap.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/bootstrap.inc,v
retrieving revision 1.461
diff -u -p -r1.461 bootstrap.inc
--- includes/bootstrap.inc	1 Jan 2011 22:46:02 -0000	1.461
+++ includes/bootstrap.inc	2 Jan 2011 22:55:18 -0000
@@ -2066,7 +2066,10 @@ function drupal_bootstrap($phase = NULL,
  */
 function drupal_get_user_timezone() {
   global $user;
-  if (variable_get('configurable_timezones', 1) && $user->uid && $user->timezone) {
+  // Do not use the timezone of the current user if the site is in maintenance
+  // because during upgrade from Drupal 6 to 7 the user's timezone was stored
+  // differently.
+  if (!defined('MAINTENANCE_MODE') && variable_get('configurable_timezones', 1) && $user->uid && $user->timezone) {
     return $user->timezone;
   }
   else {