These issues have been driving me crazy for weeks on my early 2013 macbook pro 2.7ghz with 16meg ram Yosemite 10.1. Won't bore with all the crap and just cut to the chase. I removed the CUDA driver: Cuda com.nvidia.cuda.launcher.plist (LaunchDaemons) and: com.nvidia.CUDASoftwareUpdate (LaunchAgents) AND.. ISSUES ARE GONE - both dropping of video, which was the worst one and all the graphics garbage. I have just done a successful export of a time using OpenCL. Clearly this isolates the problem and gives me a way to work. Good luck to everyone having the same issue!