Every call to a date/time function will generate a E_NOTICE if the time zone is not valid, and/or a E_STRICT or E_WARNING message if using the system settings or theTZ environment variable. See also date_default_timezone_set()
I have not been able to duplicate your problem but many others have
Google “Timezone database is corrupt - this should never happen!”
I believe that PHP version 5.3 made changes to the date() and unless the timezone was set a Notification Warning was generated. To get round this it was possible to either set the timezone or to set the error_reporting() to a lower value.
Timezone can be set in your php.ini file but does require an Apache Server reset. Easiest solution is to set the following: