I have been having the identical problem with my iBook.
Although I have not figured it out entirely I have established some facts.
The problem started when I installed an Airport card which I received for Christmas.
When my machine first failed to respond as yours did I called Apple and they suggested all of the Power Manager fixes. I tried removing all power sources, resetting, etc. No dice. The Apple rep said I would have to bring it in for service.
Instead, I went to the web and found some references to a similar problem which people had fixed by removing all power sources (battery and AC adaptor) and letting the iBook sit powerless overnight. This fixed worked, but soon the problem reoccurred.
I still get the problem occasionally but I have figured out how to fix it. The fix involves removing all power, then the airport card, resetting the computer, re-booting, then shutting down and replacing the airport card and, lastly, rebooting.
The only conclusion I have been able to reach is that a combination of the Airport card and some undefined variable (wrong keystroke, sequence of actions...) triggers this snarl. To date I have probably had to remove the airport card a dozen times to keep things rolling.
Perhaps someone out there will recognize this pattern. I described it to the Apple tech and he had no answer.
-Rod
