Hi.
I have a iMac from begining of 2006. I also registered a suddenly shutdown and restart of my iMac. Last shutdown was in the night from 04.09.2006 to 05.09.2006. I remember this because of the windows showing up and I had minimised them before I leave the computer.
For getting closer to the problem I stage my configuration to charge 100% on both kernels. I did that with a little programm, mp3player, and a second task, file salvage, for getting lost files from a HD. But that didn’t gave a result. I let these task running half a day, more then 12 hours, and the iMac runs and runs on 100% charged. But in the next night the iMac shut’s down ones again 
. Also at the next day when I was working with my Mac.
For getting closer the the problem I used a firewire HD with a fresh installed OS and let run the iMac again more then 24 hours and it also shut’s down in the night and when I was working at the next day ( Sometimes I have this behavior more than ones in 12 hours working on my Mac.
Should I backup all and send the computer to repair? And what should I tell the service?
Feeling unpleasant to send the computer out of home…
greetings
bonsai8
bonsai,
i’m also having random shutdown problems with my imac (early 2006) intel core 2ghz 20″. looking at the threads online, it seems that a majority of the victims are macbook and macbook pro users. let me know if u find a solution. thanks