Hello. I purchased the post production class some time ago. I just started watching the videos today. Pulled open Pro CC to follow along. Started project, imported video files, marked I/O, pulled a clip into sequence. Tried to do another clip, but the play/stop button doesn't work, nor the space bar. So i closed the program and started another project. Same thing this time. After 2 or 3 minutes the button and bar quits working. I can still scub through, but it will not play. Does anyone know what I am doing wrong?