Hi,
unfortunately Nvidia has broken the drivers some time ago under Windows, and Octane versions prior to 4.02.1 are no longer working with recent Nvidia driver versions.
You should need to upgrade c4doctane to v4.05-R7, fully compatible with latest Nvidia driver, and R19.
You can find 4-05-R7 by visiting your personal Downloads area:
https://render.otoy.com/account/download_archive.phpciao Beppe