JUst bought a yamaha avr. To add surround sound to my tv and it works great in HD but when watching non hd programming and you adjust the volume the tv screen goes blank audio cuts out for 6-7 seconds then it resets with the new volume level this is very annoying. My connections are as follows hdmi cable from shaw hd pvr to yamaha avr then hdmi cable to tv. Arc is set to on and I am using the correct ports on the tv and avr to support arc. Any suggestions on what is wrong???????