When press add to basket / the contact-form link it just loads forever...nothinbg happens

[Zigma]

When browsing products it goes really fast but when adding the item to the basket nothing happens. It just loads.

The same thing applies when trying to access the contact-form.php page, it just loads for ever.
What can be the issue here? I actually have no clue

Using presta v1.1
webhost: one.com

EDIT: I got angry so I installed the whole prestashop again, and replaced some files and it worked. But it buggs me that I didnt find the solution.