I have yet another issue.

I activated the guest checkout, and get again the "Please contact the store owner; some required elements of this page are missing"
I fill in the fields for the address, and get:
Sorry, we are not accepting payments from your region at this time.

The payment module is check/money order
shipping is flat rate
order total all save the COD fee

I used USA address

And no log generated.

I have commented the following in CUSTOM/css/checkout_one.css

/*.floatingBox { width: 49%; }*/
.opc-view { position: relative; z-index: 2; /*box-shadow: 3px 3px 5px 6px #ccc;*/ }

However I get the same result when restoring them.