Quite accidentally, I discovered that putting the machine to sleep and then waking it up again did the same thing. Maybe quite obvious when you think about it, but this will save me a lot of unneccesary restarts, thereby prolonging the lifespan of my CPU.
[robg adds: I'm not sure about the prolonging CPU life bit, but it will certainly save a lot of time. We've run a number of hints about deleting busy files, though none in the last year or so.]

