Figured mine out a little, my macbook pro was experiencing the same thing. Only conditions under which the keyboard and trackpad would cease responding was when the battery was powering the computer. Whenever I ran it without battery or with battery in but power cable also connected there was no fault ever appeared. I suspect the battery is getting very tired and affecting the basic instructions in the computer. Anyhow I'm due for a new battery as it tells me it needs replacing (2 1/2 years old)so I should know within a week or so that the problem is solved.