Fortunately I have never suffered from it in fact the opposite, I get more frustrated that I cannot get more of my idea's down on the laptop. At this moment my brain is two books ahead of where I am in real life. Have you ever been doing a word puzzle and you have thought of a word but it is not the correct one? No matter how much you try to dismiss that word from your mind it simply won't go away to leave you to think of the word that you really need. That is until you put the puzzle down to go and wash the dishes or walk the dog. Then your mind wanders and the word drifts away and low and behold the correct word pops up into your head.
Probably because you were not stressing over it. So if I were to suffer from writers block I would switch off the laptop and go do something else for a while. An hour, a day a week it doesn't matter, it is more important to get your book right and how you imagined it to be than to get it finished tomorrow. Go and do book related things and your imagination should start writing the book in the background.