Looks like you folks have a bug in the latest version of Catalyst. I just downloaded the latest update on 4/29, after being prompted to do so, and if I turn my monitor off and back on, the audio over the HDMI cable dies with the device showing "unplugged" in the audio properties. I have to unplug the HDMI cable and plug it back in again for the audio to recover. Simply disabling the device in audio properties and enabling it doesn't work. It's only the audio portion that is unable to recover automatically after the monitor is turned off and then back on.
I did a system restore, went back to the previous version of Catalyst and the problem went away. I can turn the monitor off and on all I like and the audio stays awake.