It always happens on a Sunday.
Whilst working on a rollout on the outskirts of Rio, I discovered that the ?/ᴏ key was not working on the laptops I was deploying.
The machine did not have an OEM installation of Windows 7, but a customised image with the Brazilian MUI installed.
To resolve I had to add this registry key and reboot.
Windows Registry Editor Version 5.00
This issue occurs with ABNT and ABNT2 keyboards.