Повторная отправка формы

<?

$file=fopen("nepster.dat","a") or die("Ошибка");
fputs($file, nl2br($_POST['content']));
fclose($file);
header('Location: index.php');

?>

<?

$file=fopen("nepster.dat","a") or die("Ошибка");
fputs($file, nl2br("\n", '<br>', $_POST['content']));
fclose($file);
header('Location: index.php');

?>

Warning: Wrong parameter count for nl2br() in S:\home\PlayRest.od.ua\www\forma\add.php on line 4

Warning: Cannot modify header information - headers already sent by (output started at S:\home\PlayRest.od.ua\www\forma\add.php:4) in S:\home\PlayRest.od.ua\www\forma\add.php on line 6
fputs($file, str_replace("\n", '
', $_POST['content']));

<?
$file=fopen("nepster.dat","a") or die("Ошибка");
fputs($file, str_replace("\n", '<br>', $_POST['content']));
$name="<br>";
$name1="<hr>";
fputs($file,$name."\n");
fputs($file,$name1."\n");
fclose($file);
header('Location: index.php');
?>

<?php
if (isSet($_POST['text']))
{
$file = fopen('data.txt', 'w');
fputs($file, htmlSpecialChars($_POST['text']));
fclose($file);
}
?>

<form action="<?php echo $_SERVER['PHP_SELF']; ?>" method="POST">
<textarea name="text" row="10" cols="100"><?php include('data.txt'); ?></textarea>
<input type="submit" value="Сохранить">
</form>