The MDD is notorious for its power supply; there was even a service bulletin about it. Mine ended up letting the magic smoke out about a year ago, so now I have several spares (sorry, won't sell them -- I need to keep this machine running for Classilla). There is argument about which is less failure prone (there are 360W and 400W versions); it was a 400W that failed in mine, so maybe they both suck. 8)

It's a shame because the MDD is otherwise a great Mac.