Hi. Having major problems with this imac I was given. For some reason it randomly shuts down. Heres a list of what it does in no particular order: * Press on switch, it makes one loud beep and monitor light flashes for a couple of seconds then stays on. Sometime it would continue to boot normally, sometimes it just shuts down. I read 1 beep means ram problem, but I have tested with other sticks. * Press power button, would chime, then shut down shortly. * Press power button, sometimes boots to the white command based screen. Tried typing "reset-nvram" and "reset-all". Rebooted to a beep then shutdown or would boot back to that white command screen. * Ran the Apple hardware checker CD, all passed. * After a shutdown, the mac booted itself up on its own after having been 10 minutes off! No idea how, it did that long beep then monitor light flashes, then it booted to the command screen I think or it shutdown. * I notice if I just brush the power switch it would often reboot, or start up with the beep. Cant see how it can be the switch as it doesnt touch the switch on the mobo by half a mm. This isnt reproducable, seems random. * Checked the PSU, no bulging caps or damage. * Replaced the battery on the mobo. * I put in a new hdd and installed Mac OS X. It seemed to work fine for hours and thought that had fixed it, until it hung and had to force shutdown with power button. Thats when the problems started again. Any one else have any ideas? I'm suspicious of the switch, or there may be a grounding problem. Apologies for the long post, but I thought best I put everything Ive tried down. Thanks. Bill