Does your display show anything indicating it is re-syncing the video? If not, it should not be a connection/wire issue. My TV has a little readout in the lower corner that tells me what input I'm on and what signal it is receiving. Anytime there is a disruption in the signal, it comes on, even if the screen doesn't blink. Anything similar with yours?

Have you tried rewinding quick to see if the blackout repeats?

You may notice that there is a hesitation in both audio and video in Series 2 Tivos (which includes the HD model) about 2 seconds after changing to a program or coming off pause most times. Perhaps your blackout is similar and is just something you have to live with from a Tivo. I have seen blackouts like this occasionally, but I never use standby since it is pointless. Usually when I see them it is in the signal and the fault of the TV network.