Core forum form dropdown empty In a D6 site, when a user goes to node/add/forum, they find that the dropdown "Forums" just shows "Please choose" but there is nothing in that menu. 

There is nothing in the PHP error log or in the watchdog.

I am sure the user has correct privileges - after all, the form does show. It's just that the dropdown that otherwise (for admin) shows all the different forums on the site, is empty, and the form cannot be submitted without it.

I've seen pretty much all the web searching for a solution, without success. Hope there's somebody in this new slick interface who will show me the right answer or direction.
Right, so I tried all sorts of illogical things, one of which was deactivating and uninstalling Forum Access module (http://drupal.org/project/forum_access). 

I did not have to - because the form was accessible - but I did anyway, out of desperation.

Then I enabled it again. Set all permissions again.

And things work!

BUT this is not a proper solution. Something in Forum Access was screwed up badly and ideally this issue should've been solved at its root, not by a workaround like mine.