I've had that message all day when trying to reserve 'Ohanas, but not with anything else. It's really frustrating that you have to put in all your credit card info before it crashes.
My Mom was on the phone with the Dining CM's for 45 minutes this afternoon being transferred all around and couldn't get the 'Ohanas reservation. They kept showing availability, but were receiving the same error message.
I just want this to be over with and it sucks that if it doesn't get fixed tonight, I'll have tons more people to compete with tomorrow when it eventually gets fixed.