When receiving a crash while attempting to create an Adaptive Skin
from a ZSphere armature, be sure to check the integrity of the ZSphere
armature itself. ZSphere armature issues are often due to errors in
the construction of a ZSphere armature.
In ZBrush 2018.1 the MultiThreading Optimizer & High/Low Priority
button options have been removed from the Preferences > Performance
Palette. These options are not longer needed as ZBrush will now
automatically optimize priority and MultiThreading.