Perdita di un file dopo l'upload

[filippo.toso]

A me questo codice funziona perfettamente:

<form name="gestisci" method="POST" enctype="multipart/form-data">              
<input type="hidden" name="action" value="upload" /> 
<input name="disegno" type="file" size="10" />
<input type="submit" name="funzione" value="Inserisci" />
</form>
<pre>
<?php
define('UPLOAD_DIR', dirname(__FILE__) . '/uploads/');  

if (!file_exists(UPLOAD_DIR)) {
    die('Destination Folder Not Found!');
} elseif (!is_writable(UPLOAD_DIR)) {
    die('Destination Folder Not Writable!');
}

if (isset($_POST['action']) && ($_POST['action'] == 'upload')) {
    if (is_uploaded_file($_FILES['disegno']['tmp_name'])) {
        if (move_uploaded_file($_FILES['disegno']['tmp_name'], UPLOAD_DIR . $_FILES['disegno']['name'])) {
           echo("File is valid, and was successfully uploaded.\r\n");
        } else {
           echo("Possible file upload attack!\r\n");
           print_r($_FILES);
        }
    } else {
        die('Invalid file!');
    }
}

?>
</pre>