According to Allt om Mac, several people have experienced problems with Macs using their optical audio out port or HDMI with OS X 10.6.8 installed.
People are reporting that the audio completely drops out occasionally and only a full reboot will solve the issue. This issue seems to happen a lot to users having their Mac Minis as media centers.
A thread in the Apple Support Communities is very active around the issue and Apple seem to have noticed the issue but whether or not we’ll see an OS X update soon, only Jobs knows. Probably.
