Is this a worse motherboard or power supply?

I'm on a HP dv9233cl laptop. My OS is Vista. I had rebooted my computer and nothing comes up just the documents window and a black screen. I rebooted again to see if it'll boot normally simply I got the same result. In the end, I had to reformat. I study it was a once thing. The front time was Monday and it happened today again. What's wrong? Can I prevent this from happening again? What can I complete? I don't want to have to keep reformatting.