audio sync issue with stereo/2.0 programming

[026163]

I've just setup my Pioneer 5.1 receiver, and have it plugged into a Samsung H260F off-air tuner, using an optical cable. I am finding that programming that is in 5.1 sound looks ok, but when the programming switches to 2.0 audio, ie news on CTV last night, the audio is out of sync.

Is this a common problem. Up until now, i've just listened to audio straight from my TV speakers using stereo analog cables. I never had any issues with audio sync. Now that I am feeding my receiver digitally, I'm getting these sync issues with non-surround programs.