trying to get object

Hi There,

I am getting below error message when click on appearence->menu.

PHP Notice: Trying to get property of non-object in D:\Inetpub\vhosts\fiskaz.com\httpdocs\wp-admin\includes\nav-menu.php on line 71

I was getting same error on line 591 but i resloved with below forums posted in wordpress
[resolved] wp-includes/nav.php – Trying to get property of non-object from wp

but i am getting problem at line 71 in wp-admin\includes\nav-menu.php