Category and content with Drupal 5.0

Hi there,

I have installed version 5.0 of Drupal and the version 5.0 equivalent of the Category module.

I have created a Container called 'Shows' and have then proceeded to create a Category called '24' which belongs to the 'Shows' category. However, when attempting to create the category, an error message is flagged up saying; An illegal choice has been detected. Please contact the site administrator.

The section that is highlighted on the page as causing the problem is the 'Categories' drop down menu. This doesn't appear to have anything in it and I wondered if anyone might have an idea where I am going wrong?

I am assuming that the Container has not been set up correctly, although it is set to allow Categories to be a child of the 'Shows' Container.

Thanks for any help that people might be able to offer.

Neil.