I'm hoping someone will be able to shed some light on an issue customers are experiencing at checkout.
If a customer enters their details as a guest at checkout, instead of being taken to the payment page, they are taken back to the beginning of the checkout process and presented with the error text for "check_shipping". We're using the All In One Shipping module and the cheapest applicable option is automatically being selected (as you can see in the screenshot), so as far as I can tell there should be no issue.
Customers are confused by this and despite my updating the error message to be more explicit (along the lines of, "update postage method and confirm details"), many cannot seem to make it through to the payment page.
I have tried the two solutions suggested in this thread, but they did not solve the issue, so I have reverted that file to its original state.
This issue is very similar to what was/is experienced by Scott, in >his thread, which currently has no suggestions.
If you wish to see the error for yourselves, feel free to give it a try at www.keshet.com.au (remember that you'll need to checkout as a guest in order to reproduce the error).