Interesting info regarding the temps you're seeing! We hear all the time "I am using other stressful apps, so my machine is not the problem". Well, I am at SIGGRAPH today and heard a funny story from someone who had a small render farm in their home for a while. They said they would blow fuses on their power circuit sometimes, but *only* when rendering with Mental Ray! Rendering with other renderers, including Cinema 4D, Arnold, and more, did not cause the issue! You can imagine, these are all high performance rendering applications that *theoretically* use system resources in a similarly demanding way, and yet only one was causing an issue. Mental Ray was for some reason just *using more power*. So I suggest you might consider that, even though many other apps work for you, the crashes might still be hardware-related. You might try a stress test application such as Prime95, or another similar option, something that is really designed specifically for stressing your hardware. Because the thing is 90+ degree temps are not normal nor sustainable for normal CPUs, and it can't really be Terragen's "fault" that you are hitting such temps, it's just doing its best to use all CPU resources (and succeeding!).
Just something to consider...
- Oshyan