I know exactly how he feels. Sometimes after I've sketched out a good plan with the characters in place, I start writing. It usually takes off at a good pace then suddenly stalls or falls apart. I ask myself, what happened? It's tough when that happens. More times than not I plow through but that usually doesn't work. I either have to go back and work on the plan or shelve it for something new and hope inspiration hits subconciously and when I pull it out again the answer will be there. It's usually not. Luckily, my file of failed plans isn't too large.