Index: excellib.class.php
===================================================================
RCS file: /cvsroot/moodle/moodle/lib/excellib.class.php,v
retrieving revision 1.12.2.5
diff -u -r1.12.2.5 excellib.class.php
--- excellib.class.php	12 Nov 2009 01:58:05 -0000	1.12.2.5
+++ excellib.class.php	29 Jun 2010 10:08:43 -0000
@@ -194,11 +194,18 @@
     function write_date($row, $col, $date, $format=null) {
     /// Calculate the internal PEAR format
         $format = $this->MoodleExcelFormat2PearExcelFormat($format);
-    /// Convert the date to Excel format
-        $timezone = get_user_timezone_offset();
-        $value =  ((usertime($date) + (int)($timezone * HOURSECS * 2)) / 86400) + 25569;
+    /// Convert the unix timestamp date to Excel date format
+        $date               = usertime($date);
+        $seconds_in_day     = 86400;
+        $utime_excel_diff   = $seconds_in_day * 25569;
+        $exceldate = ($date + $utime_excel_diff) / $seconds_in_day;
+        // Adjust the time offset        
+        $this_tz = new DateTimeZone(date_default_timezone_get());
+        $now = new DateTime("now", $this_tz);
+        $offset = $this_tz->getOffset($now);
+        $exceldate = $exceldate + ($offset/$seconds_in_day);
     /// Add  the date safely to the PEAR Worksheet
-        $this->pear_excel_worksheet->writeNumber($row, $col, $value, $format);
+        $this->pear_excel_worksheet->writeNumber($row, $col, $exceldate, $format);
     }
 
     /**