go to control panel, system, advanced, startup and recovery settings, and on the system failure section if checked, uncheck the Automatically restart checkbox. Then try again to burn media (using simulation if available). This time, if the operating system crashes and you get a blue screen, you will have the chance to write down the error message.
It could as well be a problem with the power supply. Does your pc restart by itself only when you write dvds, or has it happend randomly at other times?