Dear, I have this problem while I try to test my orders. I can`t make order, error displayed is Unable to save address, please check the input data. DEMO: https://goo.gl/Xny9ET
Seems like you have issue with your checkout.
kindly check your error log from var directory and post here for the same.
so its helpful us to troubleshoot the issue.
Even I get same error, you are losing lot of business, please fix it immediately