So I tried installing Home & placing my order on a borrowed computer. No dice--I received the same error.:
The same discounted "Latest Map" for $23.90 & the Updater Service for $47.80 were both placed into my cart on that computer, but once again, Home threw a fit at the 3rd-party verification page, being unable to maintain its secure connection.
I had the same problem last night when I tried to sign up using a American Express card. It ended up being the credit card fraud/security being tripped because of the international billing (Netherlands I think). A few minutes ago I tried signing up with a Mastercard and it worked with no problems.