I refuse to say I have writer's block, but I definitely have writer's detour. I am 16 chapters into my sequel, and I am a little stuck. I know where I want to go; I just don't know how to get there from here.
I read this same thing on Nicolas Spark's website once in his advice for writers section. He got stuck on one of his books (can't remember which one) and he said that he finally thought about the ending and outlined his way back to where he had gotten stuck.