Writerly Thoughts

Does anyone else pause in writing a story and think about it while they're away, and then go back to writing it and are surprised and disappointed to find that the thoughts they had did not magically appear on the screen and the characters are way back to where you left them? Because, come on, why are Sousa and Howard still at the party when I've totally written three more scenes after that in my head? Why is my computer not psychic?