After switching on the Pure PVR, I switched on my Denon AVR X2000. (The PVR is connnected to the TV, via the AVR by hdmi.) The TV screen blanked for a moment (as normal), then when the image returned there was an on-screen warning from the PVR: "insufficient output protection." It quickly disappeared, and everything worked normally afterwards. I have never seen this warning before. What does it mean? (I have googled it, but not found anything intelligible.) And should I worry?