I know I have one on my MBP, but PowerBooks and MacBook Pros alike have more ports than the smaller portables. Bad assumption. I could have looked at the broken iBook I have to check but I can't stand to be near it. Broken Macs break my heart
. LOL.
Have you tried the OS X disc? Leopard's Hardware Test app is right up in the Utilities bar, but I just remember that from the last time I cleaned my notebook, and you said you use Tiger anyway. You could take it to Apple if you can't find the specified drivers, supposing they are corrupted. Googling iBook audio drivers doesn't turn up much either, save a bunch of Linux forums. Linux ought to have their own computer manufacturer instead of being like MS. Then you can choose between a Mac, a PC, and a Penguin
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PowerPC laptops were not always stable, and seeing that yours has endured considerable use, it would be no surprise if it is just giving out. Then you could go get a MacBook should you choose... Oh well. See if Apple can do something for you, since they can do almost anything LOL.
-BMF