If you have a PHP configured with some open_basedir restriction (which is recommended), the WP-Codebox plugin will prevent you from exporting the posts of your blog.
Go to your blog, go in the “wp-content/plugins/wp-codebox” dir and edit the “wp-codebox.php” file :
On line 27, you should have :
include_once "../../../wp-config.php";
include_once "../../../wp-settings.php";
Well, it fails because the plugin doesn’t use the good practices, so it’s pretty easy to fix :
require_once( ABSPATH.'/wp-config.php' );
require_once( ABSPATH.'/wp-settings.php' );
I’d like to thank the developer of this plugin for doing such a great job. It brings the power of geshi (not the latest version by the way) into wordpress.