No system sounds
Since I installed OS X Lion (10.7.1), the system sounds are gone. No "hushhh" when sending Emails, no "dongg" when receiving one, no "poufff" when emptying the trash. I googled and already found a solution: Plug in a headset into the iMac's headset port and remove it again. It's ridiculous, but it works. But after a while, this happens again. I also did a PRAM-reset yesterday, but today I have the issue again. No system sounds. Music and other audio is playing fine.
Any idea what happens here and how to repair this issue?
iMac 24" | PowerBook 12" | Cinema Displ 20" | TimeCapsule | iPod | tv | iPhone, Mac OS X (10.6)