Hi
Now I see. The "none-style" pages results with a fatal error: "Fatal error: Call to a member function displayMediaThumb() on null in /usr/www/users/goldic/laforma/templates/gk_quark/html/com_virtuemart/productdetails/default_showcategory.php on line 72"
Please try download latest version of the template and replace mentioned file /html/com_virtuemart/productdetails/default_showcategory.php with the one from clean package. If this will not help rename this file to _default_showcategory.php so a default VM file will be used instead.