There was a little article in the paper today talking about daydreaming and -- get this! -- it encourages creativity.
I get some of my best ideas when I'm not sitting at the computer. I can be just idly musing about my story while doing something else, like the dishes or walking, and whamo! Something I hadn't considered leaps into my head. Or I find a solution to what's been baffling me about the work-in-progress.
This is why I think it's a mistake to assume that a writer is only productive in terms of page count per day. I'd rather have a day where I write no pages but get a fantasic idea than a day I write 20 pages. However, if I have a fantasic idea but don't do the rest of the work (ie. write the pages), that's no good, either.
To be a published writer means you have to find the balance between exciting inspiration and the grunt work, the agony and the ecstasy.
That also means if you see me wandering around with a puzzled look and furrowed brow? I'm either lost, or working out a plot problem.