A few times now I have noticed that my mac pro doesnt automatically go to sleep, and it isnt because I have a certain application open. Sometimes I just tell it to sleep manually. A few times now, I have been unable to wake it up. The light above the power button is fading on and off at the moment, the monitor is on and set to the right input, and it works just fine with other devices. I just held the power button to force shutdown, and booted it up. Now it works without any problems. The only issue I can think of that might be causing this is that I have a raid card (separate SSDs on it, nothing complicated) that has acted up a couple of times now. Any other possibilities? It's kind of disconcerting.