@App Well, I think if your computer has older hardware, that is definitely causing the error. I also think the software could be more optimized. I ran a test and did the exact same thing you did and got the error once, (my pc is very fast 1080 ti, 32gb RAM). After it crashed I did the test again and the model ran smoothly, the thing that made it run well was the fact that I did things just a little more slowly in Qubicle. I highly suggest you do the same, so don't just start clicking buttons right after you load the model. Take the time to let things load. Also, make sure you're running the latest version of Qubicle. In addition, the Qubicle creator is remaking the whole software so things will be a lot better when he releases it.
You can learn more about it here: http://minddesk.com/learn/article.php?id=108
I suggest also reading everything in the "Learn" database, like read everything (it won't take that long). You can find the main database here: http://www.minddesk.com/learn/
If you have any other problems, that cant be resolved by reading the "Learn" database or cant be solved on this forum, then I suggest contacting the developer here: http://www.minddesk.com/contact.php
Good luck! I hope I helped: