Yes, I think the G9X machines are not so great at HDMI handshake etc.

Speaking without having seen the Panasonic display, I would guess that the best option would be to output 576p (shame you have to let the G9X products do the de-interlacing) via HDMI and let your TV do the scaling as it has a much more recent design scaler built in.

The G9X has simultaneous output from component, HDMI, S-video and composite when playing discs but I am not sure if external component input is converted to HDMI. It certainly does component in to S-video out.

Malcolm