My Series2 (540) is suddenly not receiving/processing sound on any channel as of sometime after 4 AM, 4/24/09. The Letterman that was recorded 11:35 PM 4/24/09 had no sound, but perfect video. Sound from previously recorded shows works fine, and switching inputs to the TV's tuner also produces sound on all channels (so it looks like I can't blame evil ol' Time Warner cable).

The overall system's sound setup is apparently working fine, as I hear all the sounds when using the TiVo remote to flip between menus, etc., and as mentioned, I get full sound from prior recordings. Reboots and standby/wakes (2 each) have not helped. The coax is the only sound in source, and the video is fine.

So the big question: is this more likely to be a logic board problem (meaning new TiVo required), or could the hard drive (a 320 GB upg.) be failing (meaning just a new drive required)? The evidence seems to point to the former, but am I missing something? Have there been cases of JUST the sound recording/processing circuitry failing - essentially instantly? Replacing the HD is no big deal, but I don't want to go through that if the board itself has failed. HALP!

Thanks.