From RogerG: "If you do use the hibernate function, which I do and its very useful, I was told by someone who knows that at least once a week you should do a complete shutdown. This clears out any "cr--p out and stops a gradual slowing down of the system."
Agreed; fact of life. I also use CrapCleaner (or whatever they're calling it this week) before doing this. It's surprising how much does accumulate, even if nothing appears to be going wrong.
Jim