G4 mac mini shuts down randomly

Thanks for the quick response. I disconnected everything from the Mini except for the keyboard and mouse, and it still does it. We have never had a power issue before with our power coming into our house. It has always been very clean and steady. We live in a city of around 100,000 people. I don't consider it rural, although someone from Atlanta or LA would probably consider it "rural". After reading all the discussions about similar issues with the Mac Mini, I am really getting worried about this and my daughter's Macbook Pro, as well.

Thanks, again, for the quick responses. I have tried two different monitors on my mini, one our newer 17" flat screen and the other an older 17" CRT monitor. I have not been able to get it to come on at all today. This has always happened to us while we were using it. This is the exact same pattern as before the motherboard replacement. Another thing they did at CompUSA was to reset the PMU before they replaced the motherboard, to no avail. I am going to try to talk to the repair tech on Monday and see if he even tested the power brick. There is no mention of them trying a working one, which is what I wanted them to do first.

But now that it won't come on at all, again, I guess we will be taking the trip and we will be without a system for at least another two weeks. We have had Macs for 13 years now, and have never experienced anything like this. Maybe Apple needs to bring some of their retired engineers out of retirement.

Thanks for all your responses. The Mac Mini is now back in CompUSA's hands. We talked to the Mac Technician and now he wants us to send him the original CDs that came with the system. He is adamant that the original logic board was bad, and says this is a different problem. But it is doing the exact same thing it was doing when we took it in the first time. He said the Event Log is not showing a thermal error condition, so it can't be the fan. He never said whether he had tried a different power cord or not, which would have been what I would have tried first. Anyway, that is where we stand now. Can the system software cause a system to just shut down ? I have kept the software up to date with all updates applied, and had not recently updated it when this started happening.

The last answer was from someone who had this same issue and got it fixed. Can you tell me what they found was the cause of your system shutting down?

Thanks again.

Hi, can you tell me what they found was the problem on your Mac Mini?

Just for anyone who might still be interested in my problem, CompUSA called us and said they haven't done anything to our system as they are waiting on the Disks that came with the system. I had to mail them to the store. No one answered as to whether they thought system software issues could cause random shutdowns.