Dont shut your Mac down and walk away with MS Word open!! My mom did that and hours later I stepped out from the THIRD floor and heard something like a car outside. Turned out my Mom's iMac's shut down process "timed out" becuase Word wouldn't close. The iMac's fans sounded like a helicopter and I was terrified it would be wasted. I felt the computer, but it didn't feel hot at all. Seriously, I could hear it from the top of our stairway on the third floor! Just wanted to to caution folks about this. The iMac seems fine, thank goodness.