I have heard that there is no such thing as writer's block--that if you can't think of what to write you must not know your characters well enough. I offer another option. It is a universal phenomenon that I suspect most have succumbed to at one point in their life. You are simply and irrevocablly brain dead.
I lead a busy life. I work full time, am a full time mom, cook, clean, shop, get the oil changed in the car, etc. Sometimes when it gets to the time of the evening when I would ideally be able to work on my novel the only thing I am receiving from my brain material is pure static. I know that ideas are lying dormant somewhere in it, but the only thing I can think about is not having to think. This is usually when King of the Hill is turned on. Then I get annoyed with myself, feel guilty, and hear Elizabeth and Sabastian protesting that they are once again being neglected. Other times my family is more important and I need to spend quality time with them. Sometimes I can't believe how little progress I have made toward my writing goals.
"Be not afraid of moving slowly, be only afraid of standing still." I will continue to neglect my novel if it means spending time with my son and husband. I will not, however, ignore my writing completely. Even if it takes several months longer than expected, it will get done. But for now, my son is rolling around and asking for his mother's attention. And I'm never too brain dead for that.