My Screen Randomly Goes Black

At first I thought it was an overheating problem, like to protect itself, it was shutting down to cool off, but the fans still work, and it's not hot.

 

It happens frequently, without warning, the screen goes almost, ALMOST completely dark.  Like, I can still see programs that are open, but JUST barely, which means it's a screen problem, right?  I don't know specifically what's wrong or how to fix it.  So, it goes really dark, and I have to force quit.  As soon as the computer reloads, the screen is fine again, but eventually the screen goes dark again, and the whole process starts again.

 

Can someone help me?