Spilled a drink onto my phone which caused the dock connector to short out. No system sounds at all except ring tones was the symptom.
The repair is simple and doable by 90% of people. You need tweezers and the plastic pry tools. A good light will help. The repair took about 20 minutes.
One tip: make sure the microphone on your new dock connector doesn't have a clear plastic sticker/dust guard over the little hole. Make sure you remove this or you won't pick up any sounds. I'm not sure if this was an oversight in the instructions or