We found out that ordering difficults may occur when using Internet Explorer. If this happens to you, you can get around with following instruction:
If you open up Internet Explorer you should select “Tools” (off the toolbar), then “Internet Options” (at the bottom of the pop-up menu), then select the “Security” tab, then click on the “Custom Level . . .” box near the bottom of the pop-up window, then scroll down the list of items to the very bottom and click on the “Disable XSS filter” button, then click the “OK” button at the very bottom to finalize the selection. That should do the trick and you will then be able to process any orders without further problems.