Cascade Effect

To disable a menu with all submenus try to add the next code in a includes/menu.inc in the _menu_build_visible_tree Function at line 1179:

    if (module_exists('menu_per_role') && !is_null($access = menu_per_role_access($pid))) {
	  if( $access == 0 ){
		  return array();
	  }
    }

like this:

/**
 * Find all visible items in the menu tree, for ease in displaying to user.
 *
 * Since this is only for display, we only need title, path, and children
 * for each item.
 */
function _menu_build_visible_tree($pid = 0) {
  global $_menu;

  if (isset($_menu['items'][$pid])) {
    $parent = $_menu['items'][$pid];

    $children = array();
    if (isset($parent['children'])) {
      usort($parent['children'], '_menu_sort');
      foreach ($parent['children'] as $mid) {
		$children = array_merge($children, _menu_build_visible_tree($mid));
      }
    }
    $visible = ($parent['type'] & MENU_VISIBLE_IN_TREE) ||
      ($parent['type'] & MENU_VISIBLE_IF_HAS_CHILDREN && count($children) > 0);
    $allowed = _menu_item_is_accessible($pid);
<strong>
    if (module_exists('menu_per_role') && !is_null($access = menu_per_role_access($pid))) {
	  if( $access == 0 ){
		  return array();
	  }
    }
</strong>
	if (($parent['type'] & MENU_IS_ROOT) || ($visible && $allowed)) {
      $_menu['visible'][$pid] = array('title' => $parent['title'], 'path' => $parent['path'], 'children' => $children, 'type' => $parent['type']);
      foreach ($children as $mid) {
        $_menu['visible'][$mid]['pid'] = $pid;
      }
      return array($pid);
    }
    else {
      return $children;
    }
  }

  return array();
}

Please check if it works fine in your system.

Regards.