Green boot up screen?!?

I have a 2011 Macbook Pro (SSD if that matters) with the latest version of Yosemite. Its been working great, until I went to turn it on and the screen turned green. It was sort of pixelated lines of green and white. Then the green apple poped up and started a boot up. After 10 minutes a gray screen sometimes appears. I have tried to safe boot it. I have got it to boot up and work properly a couple times, but now it refuses. It won't get past the gray screen. Its out of warranty and I wanted an idea of what could be wrong before I took it in.