Hi Dab
I had this problem when I first got my 2000T and its the same on the 4000T.
It seems that if you have the HDMI and ether the scart or RCA connected together to the TV, or the scart or RCA connected into another device as well as the HDMI connected to your TV, then you will get this message come up.
If your only using the HDMI then you should not be getting this message come up, the same if your only using the scart or RCA outputs with out the HDMI plugged in.
For some reason Humax have programmed them that way I suppose.