At product page modules are abnormally appearing

-- url of the page with the problem -- : www.nfornails.eu/effect-gel-series/therm...e-turq-metallic.html
-- HikaShop version -- : business 2.6.2
-- Joomla version -- : 3.5.1
-- PHP version -- : 5.4.13

Hi.
1. At the category page everything is normal. - Attachment 1
But at a simple product page The left and right modules are abnormally appearing. - Attachment 2

2. I can't see the page with three option when asking an user to : login, register or to proceed as guest. - Attachment 3

Thank you.

The first problem solved by removing customization at the show_default.php.

Hi,

2. In the "force menu on checkout" setting of the Hikashop configuration, you can select the menu item to use on your checkout.
It seems that you selected there a menu item that has an access restricted to registered users. So because of that, when you're redirected to the checkout, Joomla actually redirects you to its login form if you're not already logged in.
So you need to make that menu item public, or select another menu item in that option.