[support] Edit permission in forums posts

[Walter Garcia-Fontes]

Drupal 5.1, with Taxonomy Access, Per-node access and normal access control.

I seem to be unable to deny edit permission to my users for forum
posts. That is, except for anonymous and authenticated users without
any role, all other roles can edit own and other's posts. I've tried
everything, like reproducing the authenticated users permissions in
Taxonomy Access and per-node access to all roles except admin, but
still: just authenticated have the right permissions but users with
roles can edit any forum post. 

Is there any other place defining these permissions that I'm overlooking?

-- 
Walter Garcia-Fontes
Barcelona