Serialize $_POST - hogyan?

így nem működik: (Notice: unserialize() [function.unserialize]: Error at offset 6 of 663 bytes)

file1:

<?php

...

$t=unserialize($vmi->getSavedPost());

...

?>

<form method="post" action="file2">...néhány <input type='text'>...</form>

file2:

<?php

...

$vmi->setSavedPost(serialize($_POST));

$vmi->save();

...

?>