Need help with WP Symposium

Check out the instructions on http://www.wpswiki.com

You need to put [symposium-forum] (copy and paste from here) on to a WordPress page. Note, lower case, hyphen not underscore.

Have you activated the plugins?
What does the Installation page report?

Swing on by the forums at http://www.wpsymposium.com and we’ll try and help you out…

It’s a WordPress complaint, for example see here: http://wordpress.org/support/topic/wp-adminupdate-corephp-gives-a-you-are-not-allowed-to-call-this-page-directl?replies=17

Are you using NextGen, seems it might be the problem, see also here: http://wordpress.org/support/topic/wp-adminupdate-corephp-gives-a-you-are-not-allowed-to-call-this-page-directl?replies=17