I have a Apple Macbook Pro that is only 3 1/2 years old. It recently started restarting for no reason when I upgraded to Mavericks. I purchased a new hard drive and installed Mountain Lion on the hard drive and installed it into the computer. It still is restarting for no reason. I can be in the middle of working on something and it crashes.
Please let me know if it is software , firm ware, or just the computer.