I have a 3 month old iMac with the latest OS (10.2.6) and seem to have lost all ability to record/playback. I'm pretty sure I have done it in the past, but I can do it no longer. I've tried using the built in mic as well as a simple mic attached to the line-in as well as connected to a Griffin Power wave. I've tried using iMovie to record something (anything!) and I've tried Bias Deck and Sound Studio. In all programs, I can see the input meter moving up and down whenever I say something so I'm pretty sure the signal is getting through. But whenever I play back, all I hear is severe crackling and popping. No twiddling with the sound preferences makes any difference. iTunes is fine so I know that my speakers are ok. Anyone have any ideas? I tried posting to Apple discussions but got no answer there. Thought you guys might be able to help!