Problemas con gestor de formularios

[adibu]

Hola amigos
Tengo un problema con un gestor de formularios que me da los siguientes errores:

Cuando entro en mi panel de control me sale el siguiente error:

Strict Standards: 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 'Europe/Berlin' for 'CET/1.0/no DST' instead in/homepages/31/d276533602/htdocs/teahorrogastos.es/machform/includes/helper-functions.php on line 38

El archivo helper-functions.php on line 38 es:

else { // not february
// check to see if the month has 30/31 days in it
if ($month == "04" or
$month == "06" or
$month == "09" or
$month == "11")
$month_in_seconds = 2592000; // 30 day month
else $month_in_seconds = 2678400; // 31 day month;
}

$in_seconds = strtotime(substr($posted_date,0,8).' '.
substr($posted_date,8,2).':'.
substr($posted_date,10,2).':'.
substr($posted_date,12,2));
$diff = time() - ($in_seconds + ($tz*3600));
$months = floor($diff/$month_in_seconds);
$diff -= $months*2419200;
$weeks = floor($diff/604800);
$diff -= $weeks*604800;
$days = floor($diff/86400);
$diff -= $days*86400;
$hours = floor($diff/3600);
$diff -= $hours*3600;
$minutes = floor($diff/60);
$diff -= $minutes*60;
$seconds = $diff;

Una vez que he rellenado el formulario y le envío, me da los siguientes errores:

Error 1

Strict Standards: 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/Berlin' for 'CET/1.0/no DST' instead in/homepages/31/d276533602/htdocs/teahorrogastos.es/machform/includes/post-functions.php on line 968

El archivo post-functions.php on line 968 es:

//insert ip address and date created
$table_data['ip_address'] = $user_ip_address;
$table_data['date_created'] = date("Y-m-d H:i:s");

$is_inserted = false;

Error 2

Strict Standards: 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/Berlin' for 'CET/1.0/no DST' instead in/homepages/31/d276533602/htdocs/teahorrogastos.es/machform/lib/class.phpmailer.php on line 1598

El archivo class.phpmailer.php on line 1598 es:

* Returns the proper RFC 822 formatted date.
* @access private
* @return string
*/
function RFCDate() {
$tz = date('Z');
$tzs = ($tz < 0) ? '-' : '+';
$tz = abs($tz);
$tz = (int)($tz/3600)*100 + ($tz%3600)/60;
$result = sprintf("%s %s%04d", date('D, j M Y H:i:s'), $tzs, $tz);

return $result;
}

Error 3

Warning: Cannot modify header information - headers already sent by (output started at /homepages/31/d276533602/htdocs/teahorrogastos.es/machform/includes/post-functions.php:968) in/homepages/31/d276533602/htdocs/teahorrogastos.es/machform/embed.php on line 42

El archivo embed.php on line 42 es:

header("Location: http{$ssl_suffix}://".$_SERVER['HTTP_HOST'].$_SERVER['PHP_SELF']."?id={$input_array['form_id']}&done=1");
exit;
}else{
echo "<script type=\"text/javascript\">top.location = '{$submit_result['form_redirect']}'</script>";
exit;
}
}else


Os agradecería que me digais qué debo cambiar porque no tengo ni idea de programación

Gracias anticipadas