My iMac G5 (10.5.8) is acting very strange lately. For some reason it will not recognize any sources of audio input. In the Sound pref pane, the "internal microphone" option under the Input tab is not even there anymore. Only line-in. In addition, when I check input levels with an external (USB) mic, I get zilch. Otherwise, this same mic works without a hitch on a G4 Powerbook. Since this is happening on two very different hardware channels, I gather it must be a software issue. However, there are other indications that something odd is happening. I reset the PRAM to try to get the audio input back. It didn't work. Instead, I lost audio output as well. Since then, every time I start up the machine, it sits with a dark screen for a long time before eventually booting up, and it seems entirely random as to whether or not audio output is working. Literally, I start up once and it works, the next time it doesn't, and the next time it does again. PLUS, a couple of times it did not recognize USB peripheries, including an Apple mouse, an iPod touch, and a flash drive. Once, I had the flash drive and the iPod plugged in at the same time, and the machine wasn't seeing either one, but when I removed the flash drive the machine immediately recognized the iPod. So this makes me think there is a hardware (PRAM?) issue after all. I am thoroughly flummoxed. Anyone have something a bit closer to a clue than I have?