I find that nl2br() doesn't convert Windows' \r\n endline sequence in POST data to an HTML <br> tag on some systems. Maybe it's because they have older PHP versions. If this happens to you, here's a workaround:
PHP Code:
function format_text($str) {
$out = str_replace("\r\n",'<br>',$str);
$out = str_replace("\n",'<br>',$out);
return $out;
} // end function format_text