I know in Drupal 6 there's an option under "Post Settings" (I believe) to "Rebuild Node Access Permissions" which then effectively rebuilds the node access table.
I've found this to be useful whenever node permissions get screwed up (ie. I've assigned a "full html" permission to a role but pages default to "filtered html").
However, on my Drupal 5.x sites, I can't find this setting. Is it available or do I manually need to edit my mySQL database?