add to card error for listing all product page

Hi i am running zen card 1.3.0.1, I config that guest can not buy the product, so when a guest click on the add product to card. i have this error:
Warning: Variable passed to each() is not an array or object in /home/ozjack/public_html/kb/includes/classes/shopping_cart.php on line 1658

Warning: Cannot modify header information - headers already sent by (output started at /home/ozjack/public_html/kb/includes/classes/shopping_cart.php:1658) in /home/ozjack/public_html/kb/includes/functions/functions_general.php on line 41

i search zen site and found some result at this link: http://www.zen-cart.com/forum/showthread.php?t=34067
i follow the instruction, but it seem to fix only the product list by catagory. it doesn't fix the product_listing_all page.

is there any code could fix this problem. thanks

Check the file:
/includes/classes/shopping_cart.php

Do you have space(s) or blank line(s) after the last ?> in the file?

If so, edit this with a proper TEXT Editor and remove those then reload the file to your site ...

Thanks Ajeh for you try to help. check on the files both the shoping card and the function_general.php, they all doesn't have any space at the end or top of the file. I think the problem is couse by "Variable passed to each() is not an array" because if I enable the guest can view the price. the problem doesn't occur. Thanks so much for you help.