Problemas con Mensajes de Error

[sebastianossa]

Hola
Podrian ayudarme diciendome a que se debe este problema en joomla y como lo puedo solucionar?. Gracias en lo que me puedan ayudar

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 'UTC' for 'UTC/0.0/no DST' instead in /home/esteban/public_html/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 'UTC' for 'UTC/0.0/no DST' instead in /home/esteban/public_html/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 'UTC' for 'UTC/0.0/no DST' instead in /home/esteban/public_html/libraries/joomla/utilities/date.php on line 198

GRacias