I've been having some problems with max 2016 view port which i initially thought was a max 2016 bug. (could still be) but have since found that it only happens when Forest is visible in the scene.
When cancelling a render with forest objects visible the active full screen view port fills with a solid colour (usually the average pixel colour). When i hide all forest objects and re-render this doesn't happen. This is fixed by exiting fullscreen again but will always happen after cancelling each render in fullscreen.
I'm using the latest Forest pack Pro plugin, windows 7, max 2016 SP1 and latest gfx drivers.
A friend of mine also has the same problem.