MacBook Pro Has Blurred Lines and Restarting

Good Day,

I have attached 2 photos of and issue I am having with my MacBook Pro (mid 2012). I am running Yosemite on it also. When I am using it these blurred lines comes across the screen then the computer becomes unusable and then it restarts. I do not know what is causing this issue, it only began about 2 months ago and happens at any time but not to often. Does anyone have this issue and know what's the cause? Also, how can I fix it?

Regards

Tyrone Harris