Here’s a shameless re-post of someone else’s great work. I’m just adding some references to Arduino and Clipsal C-Gate, Toolkit and PACA in the hope that a search engine will help guide others in similar circumstances to the fix.
Clipsal USB drivers fail to install
Same problem with the latest C-Bus Toolkit software: despite me choosing to force the install of the USB driver, the process failed.
Here’s the fix. You basically reboot Windows 8 into what looks remarkably much like safe mode, and “disable driver signature enforcement”, then repeat your above install attempts. Sweet. Thanks Kent!