Something rather odd just happened with the power supply unit for my PowerBook G4. The machine had been out on the road for the day, and on returning home, I plugged it into the mains. The indicator light on the end of the cable didn't light, and the charging icon in the menu bar wasn't present. The battery wasn't being charged. I tried several power outlets with no joy. So I did what the Microsoft Windows user within would do: I rebooted the PowerBook and tried again. It worked.