nexor

I had the exact same problem, and solved it by uninstalling the "seohelping" module, which is listed as SEO (Search engine optimization). That module is no longer present in the prestashop install package, but may remain if you upgrade from earlier versions. The issue with that module is that it calls $product->save() from inside the "actionProductUpdate" hook, which generates an infinite loop. There should definitely be a warning about this somewhere!