I have a VIZEO 26" tv with 2 TIVO units connected via HDMI cables, one unit to a port. Sometimes when I change functions on a TIVO ( like going from a recorded show to watching live TV) the TV scteen goes blue. The only reliable way to get the signal back is to turn off the TV and then restart.
I don't remember this happening when the TIVO's were connected via component/composite inputs.