I love reading your posts (not b/c you have so many problems, but because you're so god damn informative about the problem)
Honestly, it could be a number of different things. Have you tried running a stress test on the machine to see if the machine crashes during that? If so, then it's not isolated to just Nero. When a BSOD isnt generated, you can still see what caused the crash. Open up event viewer in windows look for anything thats got a red exclamation point or generally-accepted "error" sign. I dont know how experienced you are with this, but if you want to look through the system logs and post anything out of the ordinary here so one of us can look at it, I know I'd love to.
But what I'd do first is start with stress testing. Use this link below:
Use the methods their to test your hardware, and then your ram. Let me know if you have any problems or need any help. I also think that if none of that stuff turns up problems (which it should) then it could just be the CPU overheating.
But let's take it one step at a time, and try and fix this. Again, lemme know if you need help