NVIDIA contacted us with important information regarding Iray and Substance Painter/Substance Designer.
We recommend to stay with the following driver version in order to keep Iray functioning and avoid instabilities.
- on Quadro, stay with current default driver (362.13)
- on GeForce use a driver that is 362.00 or earlier
A new driver update will fix the problems, but for the moment it is best to stay on older drivers if you intend to work with Iray.