Drupal validation error when saving Mollom access keys

Hi Folks,

I'm excited to use Mollom with my Drupal site matthewcornell.org (version numbers below), but I'm getting an error setting the keys in admin/settings/mollom: "Validation error, please try again. If this error persists, please contact the site administrator." I have followed the directions carefully, and read the faqs, etc. I've also done the following:

o disabled built-in CAPTCHA (admin/user/captcha, select for all)
o run cron.php
o enabled permission: admin/user/access#module-mollom (checked both columns)

I'm at wits end, so any pointers from you would be super helpful.

* versions

site: http://www.matthewcornell.org/
drupal version: 5.1
Mollom module version: 5.x-1.8

EOM