Yamaha Receiver Problems

[mrmoggca]

Newbie here so please bare with me.
I have the Sony BDP-S350 Blu-Ray player connected to the Yamaha RX-V563 receiver with Monster HDMI Cables.
When I play Blu-Ray discs ( Shine A Light, Song Remains The Same ) both the video and audio are perfect. However when I play DVDs the audio randomly cuts in and out. Sometimes you can get 10 to 15 mins. into a disc before it starts. Other times it starts to cut in and out on start-up. While the "Cutting In and Out" is happening the "Input Chanel and Speaker Indicator" display on the receiver will flash.
As I have no problems when playing blu-ray discs I assume my HDMI cables are in good shape and all my connection are correct.
I have returned the Blu-ray player for a new one (same model) as it was thought that the problem was with the player. However the problem is still there with the new player.
So if it's not the player or the HDMI cables I'm guessing the trouble is with the receiver. Maybe I don't have something configured right between the player and the receiver?
But I don't have a clue what to do. Please, can someone HELP!