Recently, I have been experiencing monitor problems. After I have had the mac off overnight upon startup I hear the chime and the mac startups, but the screen remains grey. I did discover that if I press the green button on the iMac and put the unit to sleep for just a moment then awaken it, the monitor is fine. Tried zapping PRAM, fixing permissions, trashing system.plist. Any suggestions. I thought it might be an energy saver issue but I cannot find the preference file for that. Thanks for your time.