I am in for the challenge. I tried to register for the 5k also, but as soon as I hit continue after filling in all the info, I got the error page. I had not made it to the payment page yet. I tried to register again, but it told me I was already registered. I have not received an email for the 5k, and do not believe I have actually paid for it. I sent runDisney an email, so hopefully it will get cleared up.