This morning, I tried to turn on my iMac and it has refused to turn on. I have checked to see if everything was plugged in, and it was, and yet it is not turning on. What is worrying me is that when I try to turn it on, I keep hearing a ticking sound coming from the inside. I have an iMac Intel Core Duo which was purchased in May 2006 and it has generally worked beautifully until today. Can anyone suggest any remedies or has this computer departed to Computer Heaven? Help is greatly appreciated. Thanks!