Windows 7 - Win7 MC Audio synch problem

I have a problem with Windows 7 MC - audio is out of synch with video.

This is my set up.
Pinnacle HDTV tuner card - has analog and digital tuners.
Analog tuner connected directly to an HD antenna.
Samsung set-top box connected to tuner via S-video.

Audio out on tuner card connected to Video 2 input on HT Receiver.
Audio out on set-top box connected to Video 1 input on HT Receiver
.
Analog tuner works fine with OTA channels. Set HT Receiver to Video 2 for sound - no synch problems.

Picture from set top box is OK, but sound lags 3 or 4 seconds behind.

Please let me know if this is enough info to help.
I have expended lots of time getting the video set up and really want this to work!

Thanks