Unfortunately we do not know what settings etc you have used because we don't know what your first project was
Can you let us have details of file types used, what settings you are saving to, free space on hard drive would be good, but I suspect from the size of your drive you should have plenty.
This bit confuses meHowever, I have now tried a second new movie and it will only render to halway through on pro4. It has saved the rendered section and I burnt this to DVD, no problem, but I have no idea why it stops rendering and my computer actually switches off after it has rendered about 45%.
If it hasn't rendered you shouldn't be able to make the dvd, if it has finished, then there isn't a problem, if it does crash the pc at 45%, I'm unsure how you then managed to make your dvd?
Can you explain this a bit further.