NOTE: I did finally get this taken care of. See comments.
I purchased a 20" iMac in the fall of 2005. The computer would turn off at random times without warning. At first it would only happen once a week or so, but it started happening more and more frequently until it finally got to where the computer would not stay on long enough to finish booting.
I took the computer into an Apple dealer and they determined that the power supply was bad and replaced it under warranty.
One year and 3 months later the computer has the same problem. Only this time it went from occasional power failures to continual power failures in a week. I looked on the web and found this:
My computer has the EMC number 2056 as stated on their website. However when I called about the problem they said they would not replace the power supply because my serial number does not match their list of "affected" serial numbers.
It seems obvious to me, given that I have had two power supplies go bad in just over a years time period, and that my number matches the number that they state on their web site, and that my computer was for the correct time period that I am a recipient of their bad power supplies. But this didn't matter to their support or customer service people. I argued with them for a long time on the phone and while they admitted that they had problems with their power supplies, and that I had a bad power supply they insisted that mine could not possibly be due to the same problem because, according the their customer relations person, "if we found a problem we wouldn't send you a new power supply with the same problem". Obviously they did.
I have been an Apple customer since the early days. My first Apple was an Apple II+. I have purchased my share of Apple computers and iPods. I have had my company purchase many Apple computers for me and other employees. I have to say though that if this is how I am going to be treated when they have an obviously defective product that it is time for me to look elsewhere for my computers. So no more iTune purchases, no more iPod purchases, and no more Apple computer purchases.