I kept getting timezone errors after upgrading this box to php 5.3

Warning: strtotime() [http://php.net/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 'GMT/0.0/no DST' instead in /home/ds/ds.com/public_html/cake/libs/cache.php on line 429 

Quick fix is to simply add the following line to your core.php file located in app/config

date_default_timezone_set('Europe/London');

The list of all timezones are located here http://www.php.net/manual/en/timezones.php