SOLVED:: Unexpected Access Denied on Webform. Going plumb nuts. Trying everything.

I'm on drupal 6.25. Webform 6.x-3.18 and I have Organic groups 6.x-2.4 and a slew of other stuff installed.

I created a webform node as admin, and granted permissions to all the appropriate roles.

The form has a dynamically populated dropdown created with hook_webform_select_options_info().

That dropdown shows different data depending on the logged in user.

I log into the site from a different browser as a different user to test the code. I navigate to the url for the webform.

I get an Access Denied error !!!

The node IS published. The user IS active and has the correct roles.

I have tried writing $items['path_to_webform/%']['access callback'] = TRUE; right into hook_menu_alter.

I've installed Organic groups Webform integration in vain hope that something magic might happen.

I've installed the Trace module looking for clues, but have not yet found what is the source of the problem.

I've tried turning off webform access control with Disable Webform submission access control.

I've searched the forums without finding anything very similar.

I've never seen anything quite like this. I AM GOING SLOWLY NUTS !!!

Any clues or tips would be deeply appreciated.

Thanks for reading.