Are you using the original Yo-yo AC adapter that came with your Pismo? I had two yo-yo adapters fail on me that looked fine until VERY close examination when I discovered that both AC adapters developed frays in the delicate wires. (It appeared like little burn marks inside the semi-clear wire.)
I have since purchased a third-party AC adapter that has a thicker, more insulated wire running from the Pismo to the actual AC adapter next to the outlet. I haven't had any problems since.
Ahh.. very good.. It must be the original.. I thought I saw a spark in the wire last night right next to the plug that goes into the computer... After your message I tried moving the wire around there while trying to turn the computer on without the battery and saw a spark and computer turned on then... Thanks! BTW what third-party adapter do you use?