Hi! I am sorry to introduce a change so late in the game but checkboxes type (not singular) default values needed an overhaul. Currently you have #default_value => array(key1, key2, key3) and in #value you usually have array(key1 => 1, key2 => 1, key3 => 1) -- unless you submit the form with all checkboxes unchecked when #default_value will take over and you end up array(key1, key2, key3). This behaviour is not consistent, error prone -- other words, buggy. http://drupal.org/node/39179 has a patch. Please test it throughly. Regards NK