we got several reports that the installation of the Mental Ray products on Windows systems may fail, or may not start at all. It turns out, that this happens when the latest NVIDIA drivers (version >390) have just been installed before the plugin.
The reason is: the NVIDIA installer framework keeps some files on the system, in order to speed up subsequent installations, and to retain a history. The latest installer version coming with the most recent drivers is not compatible with the older Mental Ray installer version, unfortunately. We are working on a fix.
The latest Mental Ray for Maya installers have been fixed.
For the Mental Ray for 3ds Max installer, please try this workaround:
Rename, or remove the cache files in the directory
C:/Program Files/NVIDIA Corporation/Installer2
Then run the MR installer again. This operation will invalidate the NVIDIA installer file cache, so followup installations may need longer because starting from scratch since the installation history is lost.
Sorry for the inconvenience, and Thank You for your patience.