My wife and I got matching 24" 500GB 3.06GHz nVidia iMacs in July; my 1GHz 15" Powerbook and her 866MHz 12" Powerbook just weren't cutting it anymore. The new systems had never been opened for any reason (until last week) and I carried both out of the North Austin Apple Store. I started noting "strangeness" after watching some videos on my computer, Handbrake transcoded stuff, 30-40 minutes into the video. The audio and video would pause or just get jumbled; if I sent it to sleep for an hour, I could resume watching and things would "just work". Any other diagnosis I could think of just didn't work aside from just walking away. One time I tried a reboot -- BIG mistake. Rebooting took forever, and that was after it finally found the boot volume after a half dozen attempts. Clearly something was overheating, right? SmcFancontrol was able to reduce my problems, but not eliminate them. I was leery of going to the Geniuses with such a difficult to reproduce fail. I assumed it was my video card, but thermal data on all dozen or so sensors didn't point to anything obvious. Several weeks later, my wife started having the same problem, but worse. Simple e-mail would send her computer into terrible states, general slowness and difficulty rebooting. SmcFancontrol with all the fans turned to Max made things stable, but noisy. She ended up booting the recovery disc and while it could see the hard drive initially, after the full suite of diagnostics, the hard drive was missing. This was easily repeatable, so we went to the geniuses. After 3 days "in the shop, waiting for parts", only the hard drive was replaced. Now she's seeing great performance, no problems or complaints, and it's as quiet as ever. Time Capsule is awesome for recovery, by the way (if a bit slow to start). Definitely worth the money. So, I started seeing how to make the problem more reproducible on my machine. 30 minutes into Voyager, I saw my corruption and pauses and knew I was thoroughly hosed when all my efforts to fast forward or rewind, or restart VLC failed. I quickly copied the file to a USB stick and was able to resume playback without difficulty. Strange I couldn't get the file read from the hard drive with VLC, but Finder could scrape it off and toss it to the USB stick, but it seemed to reiterate it's not a CPU or GPU fail. Has anyone seen this type of problem before? I've seen catastrophic hard drive fails, but never flakiness. I'll be going to the Apple Store next weekend to have my machine fixed up. For the record, we don't have Applecare, but we did buy the machines with a platinum Visa that doubles the warranty.