I have a 2006 iMac that will for no reason, just power off, and then back on. It will do it when you are on it, when it is just sitting there doing nothing, there is no rhyme or reason for when it will shut off. Has anyone ever had a problem like this? It has been doing it for a couple of years now. I don't see any problem, other than being overly annoying, and anything you are working on is not saved. Thank goodness I don't do anything very important on it. I plan on getting a new one this month, if they ever are released, and wiping this one clean for the kids, but if I can make it stop shutting off, I would be much happier. Thanks in advance.