Erro no Joomla, Ajudem por favor!

[lcastelan]

Pessoal estou com um problema no meu site, está aparecendo o seguinte erro e não consigo resolver, por favor, preciso realmente de ajudar.

Warning: strtotime() [function.strtotime]: 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/Sao_Paulo' for '-3.0/no DST' instead in C:\xampp\htdocs\teste1\libraries\joomla\utilities\date.php on line 56

Warning: date() [function.date]: 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/Sao_Paulo' for '-3.0/no DST' instead in C:\xampp\htdocs\teste1\libraries\joomla\utilities\date.php on line 198

Warning: date() [function.date]: 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/Sao_Paulo' for '-3.0/no DST' instead in C:\xampp\htdocs\teste1\libraries\joomla\utilities\date.php on line 198

Valeu pessoal...