Me faltaba el codigo del principio del archivo del formulario:
Código PHP:
<?php
$file = "guestbook";
$gInfo = "";
$rFile = @fopen($file,"r");
$file_array = @file($file);
for($i = count($file_array); $i >= 0; $i--){
if(strstr($file_array[$i], "%name%")){
$gInfo .= "<fieldset><legend><b>" . preg_replace("/%name%/", "", $file_array[$i]) . "</b>";
}
if(strstr($file_array[$i], "%email%")){
$gInfo .= "<i>" . preg_replace("/%email%/", "", $file_array[$i]) . "</i></legend>";
}
if(strstr($file_array[$i], "%comment%")){
$gComment = preg_replace("/%comment%/", "", $file_array[$i]);
$wrapComment = wordwrap($gComment, 68, "<br />", true);
$gInfo .= $wrapComment . "</fieldset><br>";
}
}
@fclose($rFile);
?>