Help: losing audio on TV going from HD to SD content

[scarecroe]

I have a Sony KDL-40V5100 HD 1080p television. I play Blu-ray discs on a PS3 connected with an HDMI cable.

When I play a Blu-ray disc, the menus and HD content play fine. But when I choose content on the disc that's in SD, the audio doesn't work. I have to use the remote to change to a different input, and then go back to the PS3 for the audio to come through.

Anyone know why this happens and how I can remedy this?

[Baldrick]

What is the audio codec in the sd content? dolby, pcm, etc

[scarecroe]

On the first disc I checked, Dolby Digital 2 channel