RW Meta Box ,Problem setting post title

Here’s a solution that take’s advantage of Rilwis’ action hook… so you can profit from his nonce checking without needing to add your own.

add_action('rwmb_after_save_post', 'post_updated');

function post_updated($post_id) {

    // verify post is not a revision & not an autosave
    if (!wp_is_post_revision($post_id) && !(defined('DOING_AUTOSAVE') && DOING_AUTOSAVE)) {

    global $prefix;
    $prefix . 'name';

    // check that the custom field is being POSTED 

    if( isset( $_POST[$prefix . 'name'] ) ){    
        $my_post = array();
        $my_post['ID'] = $post_id;
        $my_post['post_title'] = sanitize_title( $_POST[$prefix . 'name'] );

        // Update the post into the database
        wp_update_post( $my_post );   

        }

    }
}

To limit this function to only run for a specific metabox, you could use this add_action instead:

add_action("rwmb_{$meta_box['id']}_after_save_post", 'post_updated');

Without seeing your metabox definitions, I don’t know what to change the ID to, so you will have to do that.

NB: Untested, but I think it is close. Please see wp_update_post() in the codex for how that function works.