Sony laptop VPCEE25FXBI HDMI sound cutting off

I just bought this laptop for Pandora and Internet Radio listening and I need help. I use the laptop HDMI with the Onkyo HDMI input. The sound is fine but it would cut-off from the Onkyo 876 and revert back to the Laptop speakers every 5/10 minutes.

If I disable the laptop speakers then there is no sound. I have to sign off from the source ( Pandora or Internet Radio) and sign on then it works for another few minutes then the same symptom happens.

Sony CRS is really at no help. Please lend a hand to a computer audio newbie for a solution.