Odd Speaker Issue

Just earlier this evening I was un-muting my iBook G4’s volume so I could play Christmas music from iTunes, and I noticed that after I pressed the mute key the feedback didn’t sound. I also tried playing music, and I couldn’t hear that either. I checked in the “System Profiler” and that showed that the sound components were in fact clearly visible and connected to the system. Restarting fixed the issue, but I knew that it would because the issue wasn’t “deep”. The odd thing about it is that earlier in the day (like the whole afternoon) my computer was taking a long long time to go to sleep, and at one point I thought I heard a small quiet popping sound, that may all have been linked, but who knows.