OSX 10.11.6, xeon w3680 6core 12thread
also Nightly 2.79 34fe3f9c069
Short description of error
Using a particle instance modifier with Children checked and Normal not checked and then attempting to change certain parameters of the particle system such as in the velocity or children tabs causes a crash. Enabling Normal in the particle instance modifier prevents this from happening.
Exact steps for others to reproduce the error
Create a Plane with a hair type particle system.
Create a cube with a particle instance modifier and set the object to the Plane with the particle system.
Check the box for Children and uncheck the box for Normal.
Go to the particle system on the Plane and check Advanced.
Drag any of the values in Velocity or Children and soon it will crash.