PICTURE PURPLE & NO SOUND

[compass1875]

I have Sky plus with magic eyes. 
My main tv can be ok then later in the day when turned back on is purple with no sound but can be ok on another tv in the house. Why is this just working on 1 tv and not the others. 
turning box off and on takes some time to do and doesn't always come back on instantly. Any ideas ? 

[Annie+UK]

Try swapping the HDMI cable around or use a new HDMI cable