My sister had the same problem. Her laptop was overheating and would just shut off because FeralHeart was taking so make to run. Even on the brand new computer I am using with a great video card (well over what you need for FeralHeart) the game makes my computer sluggish and a memory hog.
I can normally run Photoshop, a game, Camtasia, and the internet on my computer. But for some reason, when FH is up, I am lucky if I can have the internet up with it before it starts makes my computer slow down.
Try pulling up your task manager when you have FeralHeart up and see if your CPU usage or Physical Memory jumps to a higher number.
It could really only be that your graphics card is too weak for FH, which I find hard to believe in a two year old computer, your computer is overheating, or FH is using way too much memory and causing you to crash. But you would normally get a blue screen instead of the computer turning off if it was the memory.