Warning: Invalid argument supplied for foreach()

Hi how are you all?

Well my problem its that i had my worpress working perfectly and lately i have this problems, when i log in the user accom from administrator every thing funtion well, but when i log on like editor in stead of new pots a error thats say so apear: Warning: Invalid argument supplied for foreach() in /home/wert/public_html/wp-admin/includes/template.php on line 3172 can some one help me to solve this problema and please tell me why it ocure.

Than you alot for you help.