check form - save arrays in hidden fields?

I have a contact form (form.php). I check the submitted data with the same php file. If the e-mail adress is not valid I ask the user for a valid e-mail adress. Therefor I create a new form with the field e-mail. The valid date name, adress, ... I put into hidden fields, so they don't get lost. This works fine until I integreate a file upload into my form. The file data stored in the $_FILES array get lost, when I submit the form the second time (when the e-mail adress isn't valid). The same problem occours when I integrate a list box where it is possible to choose more then one item: <select name="test[]" size="3" multiple> <option value="test1"> test1</option> <option value="test2"> test2</option> <option value="test3"> test3</option> </select> Is there an easy way (in PHP 4.1.2) to store arrays like scalar variables in hidden fields, without using a database or transforming the array data into a string? Thanks, Fabian Krumbholz www.2k-web.de