I have the same problem of just losing all audio, including the clicking noise when going thru the channel menu and then selecting a channel with the Roku remote. Once it goes mute all channels are affected. No special sound system connected, just the basic Roku Express w/HDMI cable and a Panisonic TV. After 1 time (15 min), 1 time (30 min) the sound begins to become very garbled then better and better untill the sound magically becomes normal. Instead of waiting I also tried unplugging the Roku power source and replugging seems to fix the problem quickly. The 3rd time it happened I was on the Roku channel when it started.
