Over the past month or so my imac has been experiencing random shut downs. Started out with the fan turning on and getting very loud and then the computer would just shut down. I took some precautions and stopped using my computer if the ambient room temperature exceeded 78 degrees. I also opened up the back panel and cleaned out the dust. Unfortunately that did not solve the problem. Now my computer will start up only some of the time and randomly quit sometimes it quits after a minute or two some times I can get as much as fifteen or twenty minutes of use from my computer. When I opened up the panel I did not observe leaking or bulging capacitors. I called apple support and was informed that the model preceding mine is covered and the 20 in. version of my model is covered, but my 17in model is not covered under either repair extension program: http://www.apple.com/support/exchange_repair/imac.html even though my computer seems to be exhibiting the classic systems of a power supply failure. Has anyone else with this particular model of imac encountered these problems? I have been a loyal apple user since the mid 90s and over all have been satisfied with apples products, but their reluctance to acknowledge and their leisurely response in addressing the imac g5 problems have forced me to reconsider. I posted this exact same message on apple's discussion forums and it's been removed - twice! I wonder why?