Nightmares, a glitch in the system

I agree with Freud's notion on dreams.  I agree that there are ways our minds work to protect us from sleep.  However, like glitches in a system, our minds aren't perfect.  We dream in odd ways to perplex our minds, as if we're distracting ourselves from the idea that is bothering us so that we aren't woken up and disturbed from our sleep.  Maybe, sometimes our minds work in the wrong direction and in the process of creating a dream that will not awake us, our minds accidentally create a something that does the opposite, a nightmare. It is not as if the process as stopped, but rather just went in the wrong direction.  

Any thoughts?