Silver G4 - Bad Power Supply Button?

[mj1]

When I shutdown, she goes LIGHTS-OUT and then immediately LIGHTS-ON and starts up.
To shut her down I have been pulling the cord at the end of the shutdown.
I installed panther over Jaguar.
I zapped the PRAM

Is there any history of faulty power supply?

 

[theapplewhiz]

You might have a faulty power button.