Gabe here in Customer Service. Sorry if the site is giving you trouble.
If you're able to provide us with a bit of information about your web browser and platform, we might be able to see if we can duplicate the issue and resolve it. Shoot us an email via http://www.northernbrewer.com/about/contact-us/
So far we haven't been able to adequately reproduce that particular error, and reports of it have been very few and far between. We won't give up in trying to improve our site, though!
As a bit of good news, we're trying to get a new site up and running as soon as possible, and hopefully that will address the issue for you as well.
We're always available to help take an order over the phone as well. 1-800-681-2739 (option 1)