A/V Lost 5.1 from DVD-Roms

New to the site, but you folks seem to have some very insightful information.
I recently built a new system :
{Asus M4A77TD} {AMD Phenom II 3.4} {Windows 7 Home Premium64)
{Crucial Ballistix Tracer 8GB} {Asus GeForce GTX 260}
{Thermaltake V9 case} {Thermaltake 850 PSU}

I have discovered that I'm not getting all of the audio channels from my DVD-Roms. These two DVD drives were in my old system, and functioned correctly prior to moving to their new home. (One's a Samsung, I forget the brand of the second). One is IDE, one is SATA.
I have a set of Logitech X590 5.1 speakers, also used in my previous system.
When I play audio from any other source, it plays correctly, and all of my speakers are working. When I play a DVD, I get the music and sound effects, but no voice track.
I've checked the settings in both Media Center and WMP, and can't find anything set wrong. Media center gives the opportunity to test your speakers, and it only puts out sound to 2 speakers, when I have it set to 5.1.
Also, my front audio port on my case puts out no sound to headphones ( I don't know if this is relevant though).
Any suggestions or assistance is GREATLY appreciated!

 

Don't you need a lead that goes froom your drive to the mobo/sound card?

I might have made that up.

 

Thanks for the prompt response Omnituens!
I'm pretty sure that used to be the case, but they have eliminated the need for that 4 pin wire. I thought that too, and tried it yesterday, just in case. No joy. I haven't had the need for that audio cable in my last few builds.
Also forgot to mention, I've tried several DVD's in both drives, and got the same results in each case. Theses are factory DVD's, and play just fine in my ordinary DVD player.

 

If it's only outputting on 2 speakers, and you have it set to 5.1, then 4 sound tracks are going missing - including, crucially, the centre track - which is where the voices are.

Try setting the output to 2 speakers.

 

Thanks Badders. When I set Media Center to two speakers, I got all of the audio tracks, but now the image is scrambled.
Keep the ideas coming folks!
This is a screen shot of "Men Who Stare At Goats" with media center set to 2 speakers:

 

corrupt codec/media player install?

 

Agreed - try VLC or MPC-HC.

 

Thanks Krikkit! I installed both. When I tried MPC-HC, I get full audio, but no video.
When I use VLC, I get full audio and video.
Thanks to you folks, I can watch movies again! I would still like to get to the bottom of this problem though.
If I do a windows repair from the disk, would it fix my codex/media player if they're corrupted, or would I need to do a full reinstall?