I woke up this morning and discovered the server was asleep and unresponsive. I checked it out and discovered that a very strange thing happened.
I run heavily shielded spam-filtered mailboxes, every time my filter routines catch spam, a little pop up little monitor window appears. My mail is set to automatically download every 5 minutes. I get so much spam that the little popup window appears every 5 minutes, like clockwork. But apparently, for the first time, I did not receive a single spam message for a period of over 1 hour, so the popup did not pop up, and my CPU went to sleep. Oops.
My server stays on 24/7/365 chowing down the spam, it never goes to sleep. But there was a strange spam hiatus for a single hour, and my machine took a snooze. So I set it to never sleep and of course that will solve the problem. Funny that I never noticed it was a problem before. Apparently my machine has never experienced a spam siesta, it gets spam at least every 30 minutes, every day.