Mr Harvey, I’m sorry to hear that you are having problems with this your NUC since you purchased it.
I was able to read all the troubleshooting you have done on your system. At this point I just want to know if you experience the same behavior when using minimal configuration on the NUC?
Would you please remove all components from the NUC and leave only 1 memory stick and the SSD?
You can also try doing a clear CMOS.
Then, if the system does not crash, please add the network card. And restart again.
You can also try to roll back the BIOS to version 0024 and check the performance.
If the issue persists and since the NUC is still under warranty please get in touch with our Warranty Department so they can help you to replace the unit: http://www.intel.com/p/en_US/support/contactsupport