It sounds like your system got hot. If it still reboots randomly you can eliminate the CDRW as a cause by unplugging, disable that drive in BIOS and
as an added precaution set all default values there. If it still crashes, flash the BIOS. If you still have random reboots you might have damaged something else since you apparently had a short period of overheating, which can also corrupt Windows among other things, hopefully not that