I recently upgraded my php to 5.3.3 since that time ive had a number of errors the most annoying of those are below which get e-mailed to me every 5 mins. any ideas on how i can fix / stop this ?

PHP Warning:  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 'Europe/London' for 'BST/1.0/DST' instead in /home/centovacast/system/ccmanage.php on line 0 PHP Warning:  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 'Europe/London' for 'BST/1.0/DST' instead in /home/centovacast/system/class_SystemControl.php on line 0

The second

PHP Deprecated:  Assigning the return value of new by reference is deprecated in /home/centovacast/ftp/centovacast-userdump.php on line 27

thanks in advance

The first problem can be solved (as can most problems) by pasting the PHP error message into Google verbatim and following the instructions in the first result.

The second problem is due to a bad error_reporting setting in php.ini.  Follow the instructions here but for the error_reporting setting use:
error_reporting = E_ALL & ~E_NOTICE & ~E_DEPRECATED

HTH.