I just placed a test order on the site (4111 cc number, dont try to charge me, it is not going to work ).

I guess it is not SSL, but I think it might have to do with the shopping cart. I had a similiar experiences with one of our sites printcountry.com (US Ink cartridge, so not a competition to you) and it had to do with the SSL. Hope you solve it soon, I know how though it is on a business to go through this.