you should not be having these problems with a mac. how old is the mac? i would recommend for any DJ is the mac book pro. Sorry but i use both PC (my boss' comps for karaoke) and my own mac for everything else... my mac has never had an issue, its built and designed for video audio production but the PCs crash often and usually in the middle of video transition... if you are having probs with mac contact apple support they will help you
As stated previously, I also use both platforms.