Hi,
The first thing to check are the files in the folder templates/YOUR_TEMPLATE/html/com_hikashop/product/
Try to rename temporarily the folder via FTP and see if that fixes the issue. If so, then there is a problem with one of the files in that folder.
Rename each one, one by one and test if it works in order to find which one is creating the problem.
If renaming the product folder doesn't help, then the problem is elsewhere. I unfortunately cannot tell you where as we don't know ourselves. That's why I had asked a link to the page as otherwise we're looking for a needle in a haystack.