PHP代码适用于Chrome，但不适用于Firefox或IE

我哥哥有这个形式：

<form id="lista" action="lista2.php" method="post">
<input name="cf_name" type="text" size="50" hidden="yes" class="obscure">
<input name="cf_email" type="text" size="50" hidden="yes" class="obscure">
<textarea name="cf_message" cols="45" rows="10" hidden="yes" class="obscure">
</textarea>
<input type="image" name="submit" value="Enviar Lista por Email" src="imagens/lista_email.png" width="40" height="40" 
onclick="this.form.elements['cf_message'].value = lista_mail;this.form.elements['cf_name'].value = prompt('Escreva o seu nome:', '');this.form.elements['cf_email'].value = prompt('Escreva o seu email:', '');">
<input name="submit2" type="submit" value="Enviar" hidden="yes" class="obscure"> 
</form>

这调用了这个 PHP 文件：

<?php
if ( isset($_POST['submit']) ) {
// Dados de autenticacao SMTP
$smtpinfo['host'] = 'localhost';
$smtpinfo['port'] = '25';
$smtpinfo['auth'] = true;
$smtpinfo['username'] = 'xxx';
$smtpinfo['password'] = 'xxx';
// Dados recebidos do formulario
$nome = $_POST['cf_name'];
$email = $_POST['cf_email'];
$mensagem = $_POST['cf_message'];
// Inclusão de ficheiro PEAR. Certifique-se que o PEAR está activado no seu alojamento
require_once "Mail.php";
// Corpo da mensagem
$body = "Nome: ".$nome;
$body.= "'n'n";
$body.= nl2br($mensagem);
$headers = array ('From' => $email,
'To' => $smtpinfo["username"],
'Subject' => 'Encomenda Website');
$mail_object = Mail::factory('smtp', $smtpinfo);
$mail = $mail_object->send($smtpinfo["username"], $headers, $body);
if ( PEAR::isError($mail) ) {
echo ("<p>" . $mail->getMessage() . "</p>");
} else {
echo ('<b><font color="FFFF00">Mensagem enviada com sucesso.<br><br></b>Seu email: ' . $email . '<br><br></font>');
}}
?>

这基本上会发送一封电子邮件，其中包含一些选定的产品，名称和电子邮件。

问题是它在Chrome上完美运行，但在FF或IE上则不然。按下提交图像时，URL 将更改为 PHP 文件，但会显示空白页。

编辑：

添加了这个：

ini_set('display_errors',1);
ini_set('display_startup_errors',1);
error_reporting(-1)

FF/IE 显示空白页且未发送电子邮件，Chrome 会发送电子邮件并显示以下内容：

Strict Standards: Non-static method Mail::factory() should not be called statically in /var/www/vhosts/[site url]/httpdocs/lista2.php on line 33
Strict Standards: Non-static method PEAR::isError() should not be called statically, assuming $this from incompatible context in /usr/share/php/Mail/smtp.php , dont know if it helps

关于"隐藏"字段的提示也无济于事。