The one part of software engineering that gets annoying is once I get into a project, my mind is constantly designing, debugging, etc.. I've solved many a problem in my sleep or doing some entirely unrelated activity. Having said that, a few years ago, I woke up in the middle of the night with the perfect solution to a problem I was wresting with. The next day, I quickly started implementing this brilliant idea. It soon became apparent that it was actually one of the dumbest ideas ever; not only didn't it solve the problem, it did so in a very complicated way and would have introduced even more problems.
Anyone who thinks he has a better idea of what's good for people than people do is a swine. - P.J. O'Rourke