Yep I think u have it TD...you are apparently lucid but cannot move that is the whole weird thing takes 20-30 seconds to come out of it
So the cure is? and why do you wake up? must be a medical explantion surely?
Google is a wonderful thing when you have a clue
http://www.nightterrors.org/
Think I can probably narrow mine down to stress although I believe my mother may have similar episodes so heredity may come into it