See post 169. I have had a similar issue, but when mine blacked out during a recording it rebooted. I haven't experienced the increased audio.
Many versions ago, my HWS would black out and then come back if I deleted a recording from a very long list -- the criteria seemed to be that the list had to be long enough to trigger the bug where scrolling past the end of it would cause the current screen's worth of entries to scroll rather than jumping back to the beginning of the entire list. I don't remember if this would interrupt a recording or not. The only thing I remember for sure is that it didn't do a total reboot because it came back on after a second or two, but the broadband icon in the banner would always show as disconnected for a while. I hadn't had one of these blackouts in a long time, until two nights ago.