Do not hit the "Update Registration" button at the top of the screen. When you are in the window selecting your airports there is a scroll bar immediately to the right of the window that shows the airports. Scroll down, it will ask for your zip code and Rapid Rewards # (if you have one). Then there is a "Register" button under the Rapid Rewards box. Click THIS register button (not the 'update registration' at the top). That should work. If it doesn't try turning off any firewalls that you have running. I was setting up my MIL's DING last nite (she was having the same problem/error as you are). Her Norton Antivirus was causing a problem (along with the fact that she hitting the "wrong" register button). Once we got her registered we turned Norton back on and all was fine and she got her first Ding an hour later