Hi there,
I found a bug in Terragen concerning the power fractal shader v3.
Repeat these steps to recreate the crash:
1) open a new or just any scene
2) in the node view, create a new power fractal shader v3. Do not link this to any other node.
3) right click node > open preview in new window
4) right click node > settings
5) start changing values (like color contrast and offset... or feature scale, etc.) for a minute or so
6) crash
My system:
Terragen 3.3.03.0
Windows 10
i7 3930
770 gtx
asus x79 pro
32gb DDR-3 1866