Cox mini box problem

Ever since I changed to an HDTV in one of my bedrooms, the picture is very bright, pinkish,  and no volume when I put the tv on.  I have to reboot the mini box EVERY time I put the tv on to get a clear picture and sound.   

I thought the mini box was the problem, so I replaced it today and it does the very same thing.  EVERY time I put the tv on it is very bright, pinkish, and no sound.  Again, I have to reboot the mini box and it comes back clear and with sound.  What is the problem?