Good morning everyone. I've learned quite a bit from this site in recent weeks as I found it following my purchase of a 20" iMac (2.66 GHz) a month ago. I've got a question for the group and I'm quite certain it's a stupid one so please be gentle. As I do every night, last night I put my iMac to sleep at around 11:15 pm before going to bed. Upon awaking this morning I couldn't get it to wake up. Hitting keys on the keyboard didn't do it, nor did moving the mouse around. I'm not sure if this is important but both my keyboard and mouse are wireless. Power to the other things on my desk was still on so it wasn't a power problem. Anyway, I hit the power button on the back to see if it had simply shut itself off and . . . nothing happened. I hit it again . . . still nothing. Finally, hitting it a third time did the trick and the computer roared to life and came on normally. It had never done this before. It had always immediately awakened in the morning upon hitting a button on the keyboard. First, is this common for an iMac to shut itself down? Second, why would the power button be unresponsive? Finally, if the machine had actually not been off (which I doubt very seriously) did I do a big "no no" by hitting the power button to turn it off/on? Thanks for your replies.