The reason you are having trouble accessing the shopping cart might mean a problem with the cookies setting on your computer. It may have expired or not set properly, causing you to be booted out. Sometimes though its just one of those "internet" things, which can happen.
All we can suggest is that you try again and see if you are still having a problem ordering. If you are, please call our Toll free number 1-866-560-6348 (6am to 6pm PT Monday to Friday) and order over the phone, or if you want to ask for technical support, they can arrange for one of our technicians to call you back.