Are dark night problems a common thing? It worries me that if I practice they might happen Are dark night problems a common thing? It worries me that if I practice they might happen:

http://m.theatlantic.com/health/archive/2014/06/the-dark-knight-of-the-souls/372766
Yes, passing through what you called "dark night" is a prerequisite for Enlightenment.
The term refers to existential crisis experienced around the time of fully realizing Emptiness and the Three Marks of Existence. In Vajrayana tradition this is also referred to as the death of the ego. As Chogyam Trungpa said, 


  Enlightenment is ego's ultimate disappointment.


(On a separate note, I would not blindly believe anything I read on dharmaoverground.org -- that community does not seem to be grounded in genuine teaching.)