AbleCommerce Shopping Cart Software

Other than design customizations we have no code changes on the checkout pages. The system will no longer allow existing customers (not verified for new ones yet) to ship to an address OTHER than the billing address. If you try to add the new address, it appears to take it but if you look back at the address in the "ship to" area it shows the same address as the billing, the new address you entere is just lost. Sometimes in the error log we see an error in the error log:
"ERROR 2010-08-08 13:09:38,473 23006824ms Object a - An error has occured at https://store.gourmetsleuth.com/Checkout/Default.aspx
System.Web.HttpUnhandledException: Exception of type 'System.Web.HttpUnhandledException' was thrown. ---> System.ArgumentNullException: Value cannot be null.
Parameter name: countryCode"

I have tried test orders and I have several "ship to" addresses associated with my account. I tried to select one and save it, the screen refreshes and shows errors saying the credit card data is missing.. very odd.

What is your application version? Make sure that you didn't made any change to checkout code, you can compare current checkout file with the default one.

Again, we just upgraded to 7.05. We have zero, no changes to the the checkout code.
The cart/customer gets a 404 error if you try to add a different address. In the error log you'll see a "missing country code" error.

**UPDATE**
This was our error. The business/residental drop down was incorrectly commented out.