I would like to report a bug.
Always when we use the IPR render of Vray 3.5 and try to change any parameter of Forest color the Max crash
Tested on MAX 2016 and 2017
Vray 3.5.04 and 3.5.03
Forest - 5.2.4(Beta) - It also happens with 5.2.0
Also reported the error to the chaos group.
I hope it helps with something