MacBook Pro keeps turning off!

My 2012 MacBook Pro keeps shutting off on its own. No screen saver comes on, but I am able to wake it up sometimes by moving the mouse. Other times I need to hold the power button. The white blinking light on the front remains on. This has been happening more & more lately. About 2 years ago I upgraded the software from Leopard to Snow Leopard using a purchased disc. I have not upgraded since. It will shut off even if I am working on it! Any ides??
EDIT: should mention also that for the last year or so, whenever I open the Mac (after shutting it, not powering off), I've been getting a "clanking" noise, like it inserted a disc, and a gray screen with a progress bar. This never used to happen. Definitely feels like something is wrong with this computer; I have an OLD MacBook Pro from 2006 that I still use and it has had NONE of these issues im describing.

If I were to guess I would say it is overheating. The only thing I could think of that could make a "sound" would be either a dvd or cd in the superdrive, a mechanical hard drive that is dying (if your drive is an SSD this would not make any noise) or one of the internal fans is going bad and dying.

If it is overheating one of the fans could be going bad and either not working or working slowly causing overheating. Macs will shut down if they are overheating to prevent damage.

There are apps that will tell you your internal temps and what RPM the fans are running at. I use iStat but it cost $2.99 in the app store. There may be others that are free.

The other option is taking it to a local genius bar. They will most likely diagnose for free and that would give you a place to start.

ifixit.com has all kinds of repair help information too.

Lisa

Thanks- that sounds pretty likely, I've noticed it has been getting hotter than usual. I'll take it to the Genius Bar today!