My PowerBook is in for repairs. There was a two or three day history of sleep-wake problems. The first thing I noticed is that it wouldn't wake up one morning after an overnight sleep. I overcame this, but it was by no means simple. None of the usual efforts worked: holding down the Power button, hitting Command-Control-Power, removing and replacing the battery. After a bit of Google work, I discovered Apple's instructions for resetting the Power Management Unit, which, for my model, involved removing the battery, pressing the Power button for five seconds, and replacing the battery. This didn't quite work: it did reset the machine and allow a reboot, but the PowerBook fell asleep again at the login screen every time.
Eventually, I got it up and running for several hours using a very low-tech solution: I shut it down, removed the battery and the mains power, and let it sit for an hour. I plugged it all back in and it worked. Until the next day, at which point I decided it was time for repairs.
I took the PowerBook to the Next Byte Apple Centre on Glen Osmond Road at Glenunga. I had purchased something there before, and I seemed to recall that they did repairs on-site, rather than sending items away. That, coupled with the fact that I didn't want to drive into the city on a Saturday morning, sealed the deal. The guy who served me was great—very efficient, and understood the problem. (The PowerBook itself was kind enough to demonstrate the problem first time—I was fully expecting to get there and have it wake from sleep as normal.) This helped to offset the fact that they were charging me $A 75 just to get someone to look at the problem. Somehow, I don't think this is going to be cheap.