maybe you forget add square brackets?
orig
if (is_admin())
add_action('manage_pages_custom_column', array(&$this, 'cpdColumnContent'), 10, 2);
add_filter('manage_pages_columns', array(&$this, 'cpdColumn'));
// column post list
if (is_admin())
add_action('manage_posts_custom_column', array(&$this, 'cpdColumnContent'), 10, 2);
add_filter('manage_posts_columns', array(&$this, 'cpdColumn'));
mod
// column page list
if (is_admin())
{
add_action('manage_pages_custom_column', array(&$this, 'cpdColumnContent'), 10, 2);
add_filter('manage_pages_columns', array(&$this, 'cpdColumn'));
}
// column post list
if (is_admin())
{
add_action('manage_posts_custom_column', array(&$this, 'cpdColumnContent'), 10, 2);
add_filter('manage_posts_columns', array(&$this, 'cpdColumn'));
}