It's not always that you sell something wich needs shipping. Can you please considder making the shipping option selectable and not mandatory? See also http://answers.websitex5.com/post/34090

This makes your software more usable in different situations without any disadvantages.

You can sell for instance space, information or software wich can bee send by mail. So no shipping is necesary so the shipping option should be set off totaly in X5