Update won't install, CD won't play

Question

I know, odd combination of problems.
I have no idea if they are connected, but the other day I ran Software Update, the latest update for Leopard was available (10.5.4, I think), I got a warning that the computer wasn't attached to a power source, I had a full charge and was confident I had plenty of power, so I tried to proceed with the update. When I restarted, the progress window came up, telling me the installation had begun, the blue bar got about 1/8th of an inch from the starting gate and stayed there, and stayed there.
I had the time, so I just left the room and mowed the lawn, and when I came back there had been no progress, the computer was frozen as best as I can tell, so I shut it down and restarted. This time the install window didn't come up and I was able to get it to boot fully. I ran Software Update again and it told me that the same update was available, which gave me the impression that it hadn't installed the first time.
I tried again, this time with the power adapter plugged in, I didn't get the warning about not being plugged in, but the install froze at the same point.
Then, later that day, I inserted a CD that I wanted to rip, the Superdrive made the usual noises, but they last longer than usual and eventually the CD just ejected. Usually, if iTunes is not open and I insert a CD doing so will open iTunes automatigically. This time no. I tried opening iTunes first and then inserting the CD. Same thing happened. Ejected. I scanned some threads here and tried another recommended trick, holding the Powerbook so that the slot for the Superdrive was facing the ceiling, but that didn't work either.
I just bought this machine from an Apple certified technician, I know it's risky, but I trusted him and wanted this 12" form factor more than anything else on the market. I'm totally bummed about this, so any help would be greatly appreciated.
Thanks!

Answer 1

Thanks for the response, especially since you are the only person to respond, but I checked out the link you provided and it doesn't sound to me like that is the problem at all:
+Over time, the settings in the Power Manager may become unusable, which can result in operational anomalies with the computer. Examples include not turning on, not waking from sleep, not charging the battery, or not seeing the AC Adapter, among others.+
+Resetting the PMU is not intended for resolution of a stall or situation in which the computer is unresponsive. A PMU reset should not be necessary except as a last resort in cases where a hardware failure of the power management system is suspected. Performing a PMU reset returns the iBook and PowerBook hardware, including NVRAM, to default settings and forces the computer to shut down.+
+For most situations, a restart is sufficient. If the computer has stopped responding, try these steps, in order, until the computer responds:+
+1. Force Quit (Option-Command-Escape)+
+2. Restart (Control-Command-Power)+
+3. Force Shut Down (press the power button for 10 seconds)+
+Only perform a PMU reset on the computer if none of the above steps resolved the situation.+
I have not been having any problems at all charging my battery or using the power adapter. I mentioned the power error, but I really think that that's more of a word of caution and a suggestion that it's best to be using the power adapter when for update installation because you want to make sure not to run out of power. But, I chose to proceed using the battery precisely because I have so much faith that it was fully charged and would last plenty long for the download and installation to run. Also, it specifically says that the reset should not be done if Force Quit, Restart, or Force Shut Down are working, and they indeed do continue to work.
So, with all due respect, I'm really hoping for some other ideas.
Thanks!