На всех страницах появились сообщения "Warning: mktime() [function.mktime]..."

Warning: mktime() [function.mktime]: It is not safe to rely on the system's timezone settings. You are *required* to use the date.timezone setting or the date_default_timezone_set() function. In case you used any of those methods and you are still getting this warning, you most likely misspelled the timezone identifier. We selected 'America/Los_Angeles' for 'PDT/-7.0/DST' instead in /home/lacible/public_html/libraries/joomla/utilities/date.php on line 117

Кто-нибудь встречался с такой проблемой? Где что исправить?