I hope forum members don't mind me posting this here (as well as the Apple forum). There's so much experience and goodwill here, and I'd be very grateful for some feedback on this issue of mine. My 15" MBP C2D 2.33 with a Hitachi 160 GB drive is vibrating gently. It seems to emanate from the left hand side, next to the track pad. I know it's the hard disk because when the drive occasionally sleeps the vibration stops (and the almost inaudible fans carry on). If you have a similar set-up, please put the laptop on your lap or on a soft surface and feel the metal surface on the left. Can you 'feel a hum' in your hand? A bit like touching an electric shaver. Is it perceivable on other parts of the computer too? The vibration almost completely goes away when the computer is on a firm, flat surface. I don't want to make a fuss about something that is normal but I don't want it to lead to problem later on. Apple are willing to exchange it but I also don't want to waste their / my time. Thanks for the help, everyone.