Did anyone [with this issue] ever get to the bottom of why TiVo temporarily loses signal and re-handshakes the HDMI intermittantly? 

It bugged me for ages then I noticed that it only does it for me when I watching TV2.  Is this to do part of the signal being broadcast?  I can't think of any other reason why this only happens on TV2.  Not as bad as it was but can be annoying when it decides to do it 3 or 4 times in an hour.