This is a bit of an older thread, but I'm having the same issue.
Has hikashop changed a little? I can't seem to follow your directions at all.
Go in the menu Display>content modules and edit your HikaShop products listing module. There, in the "menu" option select a category listing menu item. Then, click on the "joomla module options" button and in the "menu assignment" option of your module, make sure that the menu item that you selected in the "menu" option is not checked.
This makes no sense to me. Display where?
in hikashop? Hikashop display menu has no content modules in it. It's the view and custom view area.
I have the slider module assigned only to the home page, but the problem is when I click a product off the home page it keeps the menu at the home page.