Here's a strange one... I have a MacBook Pro running OSX Lion (10.7.3). Recently, I have noticed that it will occasionally stop making system sounds through my external speakers. Playback from iTunes, etc. seems to work fine. Now, here's the strange part. When I unplugged my external speakers to plug in my ear buds to make a conference call via WebEx my computer suddenly started playing ALL of the systems sounds that had been saved up. As my machine had been on for several days, this playback took about 5 minutes of bings, bongs, and swooshes. This same behavior happened again today. I noticed that the system sounds had stopped so I unplugged my external speakers and my machine made all the sounds from the past several hours through the internal speakers. Any ideas on what's going here? Thanks!