We have one client who was unable to complete checkout in our shop using his Mac desktop computer.
He sucessfully added a product and entered his postcode in the side cart.
After clicking on the 'proceed to checkout' button the checkout page displayed as per this image:https://app.box.com/s/ie72qx4i9ea7ve7psmc2jy8537pbaywf
As you can see in the image, there are no checkout fields and there is a message across the top that says 'one item is missing'
Note that he then used his phone and was able to successfully complete the checkout on his phone.
It seems that the above error was reproducible as he provided the screen shot later, so must have tried the process again to create the screenshot
We have had over 100 succesful transactions since launching the shop, with only this customer having a problem.
What sort of error should I be looking for here?