I have the same problem.

Using: Linux 2.6.18; PHP version 4.4.9; MySQL version 4.1.22; Zen Cart version 1.3.9h; browser IE8. You mentioned to check for SPL support. Did not see it mentioned in list. How do i go about activating it in my php.ini file?

Error message does not appear in admi, but found it in the /cache folder under xxxxxx.log :

[08-Nov-2010 03:04:39] PHP Fatal error: Cannot instantiate non-existent class: recursiveiteratoriterator in /home3/user_dir/public_html/admin_folder/backup_zc.php on line 44

Could you give me some guidance with this?