I previously posted about placing a small computer fan blowing directly on my Roku Express and it seemingly fixed the problem of losing sound. This is an update to that post. I am not experiencing the loss of sound near as much, maybe once a week now. I also found if I power cycled my TV the sound would come back but only when it totally lost sound. I have also experienced the sound "fluttering" and the only way to correct the problem is to power cycle the Roku.
We are looking for a new TV for our bedroom and you can bet your rear we won't buy one with Roku built in. We are also looking for new streaming devices.