Mac problems

During the production of our video using the mac book at school the laptop we had was consistently rebooting before we could save the work meaning we had to redo a few scenes and even start the entire project again when it failed to boot the hard drive with our data on it. It also had a few faults within the programs its self that wouldn't allow us to add a few effects we wanted to add into the video which resulted in the lower quality of resolution of the video as we found it was the only method to play the video without the entire screen going completely black through playback and even on YouTube there is a notable difference between the draft video and the final video.