Usually these things are related to hardware or drivers. If you changed anything recently before this started happening, it would be the first thing to examine. For example if you recently upgraded ram, I would suggest testing it. It certainly didn't ship with 8GB at that time, and I don't know whether that was a very recent change. The logs you pasted there aren't helpful. I would follow Marvin's suggestion. They may provide some clue.
6/17/15 at 5:06pm