So if all my other recent hardware troubles weren't enough, my Mini (1st gen Intel, 1.66Ghz core duo, 2GB RAM, never opened by me), shut itself off suddenly three times while playing EyeTV recordings (the last two times one after the other). After being left off for a couple of hours it worked fine.

My only thought is that it is overheating or incorrectly thinks it is overheating. Why it would all of a sudden is a mystery. To make things even more fun I have 10 days left on my AppleCare. I'd take it in immediately if I could reproduce this at will but I can't -- last night we watched two hours of EyeTV -- no adverse effects.

Maybe it is just Apple's subliminal sales department trying to get me to hurry up and buy a MacPro.

Any advice on the Mini?

Look at the system.log.

Report the problem to Apple before your AppleCare runs out. At least you can challenge them on it if they can't figure it out and fix it, and it gets worse after the AC runs out.

Does it have any other weird behavior other than the shut downs? A shutdown also can be caused by problems in the power supply. You should do a good dust out with some air on the fans. Sometimes they can get gunked up with dust and hair enough that they don't spin right.

Report the problem to Apple before your AppleCare runs out. At least you can challenge them on it if they can't figure it out and fix it, and it gets worse after the AC runs out.

Does it have any other weird behavior other than the shut downs? A shutdown also can be caused by problems in the power supply. You should do a good dust out with some air on the fans. Sometimes they can get gunked up with dust and hair enough that they don't spin right.
Dust wouldn't surprise me at all our building has been a disaster area for the past year, but is there a way to do it without opening the machine. or I need to pry it open? I wonder if the Apple Store geniuses can give it the compressed air treatment.

Seriously, check your system.log. It will give you the reason why it's shutting down. If there's a thermal problem, it will be in the log. If it's a bad power supply, it will be in the log.

Seriously, check your system.log. It will give you the reason why it's shutting down. If there's a thermal problem, it will be in the log. If it's a bad power supply, it will be in the log.
I did look at it this morning it was Greek to me -- are there any keywords I can search for? But would it have had time to write anything in the log -- the shut off was exactly equivalent to someone pulling the plug.

You need to look around the time it happened. If it's a thermal event, you'll see thermal messages before it shutdown. However, in my experience thermal events trigger sleep to prevent data loss. Also, each time a Mac boots up, there is an entry for what caused the previous shutdown.

Look for this line:

Mar 19 09:57:10 localhost kernel[0]: Previous Shutdown Cause: 5

#5 means I shut it down via the Apple menu. Other numbers mean different things. You can Google the message to find out what the other codes mean.

Thanks, Jason! Very helpful -- I'll look tonight.

in my experience thermal events trigger sleep to prevent data loss.Well, remember the original MacBook? The one (which I am typing on right now) that had a bad temperature sensing system due to the way a wire was run across the processor? You'd be just working away, no problems with any temp readings, then blam, the machine would shut down. No warnings, no nice sys.log entries to give clues. It took apple almost 9 months to get it figured out and a firmware update out the door.

Not that I'm saying that Ted's Mini problem is in any way related to the early MB issues. It's just that instant powerdowns can be one of the most vexing problems to diagnose and fix. Oftentimes it can be traced to a logic board gone bad. Board gets warm, parts expand, solder loses conductivity, and current ceases to flow somewhere = shutdown. I've got a pile of dead Macs in my shop with bad logic boards that are too expensive to replace.

From the system log, only one of the three sudden shutdowns left a cause message:

3/17/09 12:01:37 AM DirectoryService[11] Improper shutdown detected
3/17/09 12:01:40 AM kernel Previous Shutdown Cause: 0

Sill googling cause 0