iPod seizures

VanPod had the closest thing to a heart attack just now – multiple times. I docked it to my PowerMac and it kept on restarting. Which is exactly what happened to my sister’s 15GB iPod which I bought for her. 2 AppleCentres quoted a high price to fix the problem, which was apparently quite serious. (She ditched it for a new iPod instead)
VanPod is back to normal now – I managed to eject it without problems. But it’s made me wonder, is it something we’ve both done to our iPods, that made them behave this way? Is it a setting in our power supply?