Try going to the Hardware section in Preferences and increasing the sound device latency value (it may be called buffer size - it varies according to what it's connected to). This may also make a difference to your playing stop on one track too, although that sounds more like a HDD buffering issue. But it's a Mac - I have no idea what you have to do to optimise the performance of one of those for audio. But there are almost certainly things you can try - googling 'improve mac performance for audio' will produce several suggestions.
Thanks for your thoughts. But I don't see why there should be any latency / buffering. This computer is brand new and optimized for working with programs like Audition.
This has nothing to do with how wonderful your computer is. If you haven't specifically optimised it for audio, then it isn't - it's that simple. All computers experience latency and buffering issues - it's inherent in the way they work. It takes a finite amount of time to process anything - especially feeds from a hard disk to a sound device, and that's why there is a buffer built in - it simply wouldn't work at all without it. And yes, you often need to alter the size of it, depending upon what you are trying to stream from the drive.
With all due respect, I suggest that you actually try what I've suggested before telling me it's unnecessary.