QUOTE(1024kbps @ Jan 16 2011, 03:19 AM)
Install other codec pack wont help

CCCP is not just
another codec pack. It automatically sets 5.1 audio to stereo channels. It seems like TS's problem is beyond CCCP's auto setting. So let's try this.
TS, did you remove ALL OTHER codec packs and media player except default Windows Player? If so, have you tried opening your movies with Media Player Classic? Make very sure that the movie is loaded by Media Player Classic. On your taskbar there should be a blue icon saying FFA on your taskbar below.

Click it, and you should see this screen.

Make sure the Mixer is set to stereo. Now you should be getting all channels including speech.
If someone were to cancel your speech channel for a karaoke session, he would set your speakers to 6 channel and leave Front Center box unchecked, like this.