Portected gmes work for a while then stop. How come?

[Raven666]

I started playing Spyro 3 Year of the Dragon and I beat about 75% of the game. I didn't play it for a few weeks. Then when I tried to play it again I got the softwear terminated message. How come it worked for a while then crashed.

Also when I play Ninaj shadow of darkness when i get the the end of he first level the screen just goes black and nothing loads. This also happened when I first tried to start the game for the first time.(after making the backup copy)