As far as I understood this right, you want to disable the possibility to reach any other side aside from the dashboard.
Well, then here’s a short plugin for you:
<?php
! defined( 'ABSPATH' ) AND exit;
/* Plugin Name: (#45989) »kaiser« Allow Dashboard only access */
function wpse45989_access_dashboard_only()
{
if (
! isset( get_current_screen()->id )
OR 'dashboard' !== get_current_screen()->id
)
{
// Lets limit this to only specific user roles
if ( current_user_can( 'ROLE_NAME_HERE' ) )
exit( wp_redirect( admin_url() ) );
}
}
add_action( 'current_screen', 'wpse45989_access_dashboard_only', 100 );