v3.19: permanent cart reload issue with vm + klarna checkout

After upgrading to Storefront 3.19 we ran into big trouble: Our cart will repeatingly reload every 1-2 seconds. so customers cant't enter information. So the site is completely broken for the moment.
The 3.19 update-file that triggers the issue is here: gk_storefront/html/com_virtuemart/cart/default.php
After restoring this file to the 3.18-Version the issue is gone and the cart works fine again (although then we have other issues i.e. with VAT - so we were really looking forward to 3.19). We use most recent Joomla (3.4.5), most recent VM (3.0.12) and most recent plugin (Klarna Checkout). We would really appreciate any help

Hi

Please send me an access to FTP and url to Your site.