Problem playing stereo audio files

I'm using Windows XP Pro and when I play an audio file in Windows Media Player 11, instead of playing the left channel out of the left speaker and the right channel out of the right speaker, it plays the left channel out of both speakers.

I tried using different speakers and it did the same thing.

I also tried reinstalling the audio drivers, but that didn't work either.

When I change the balance in the graphic equalizer in WMP from 0 to -100 there's no change at all, when I change it from 0 to 100, nothing comes out of the speakers.

I tried re-ripping one of my CDs, but that didn't work, so it's not because it ripped it wrong. The CDs play correctly in my stereo, just not on my computer.

I tried changing my speaker setup in the Windows control panal to mono speakers so it would just play it in mono so I can hear the songs right, but that did nothing.

The only thing that worked was when I converted one of the files to a mono mp3. The file has both channels, I just can't get it to play both without converting it.

I don't want to have to convert all my music files to mono. Any ideas? Has anybody had a problem similar to this? What else can I do to make it play stereo correctly, or how else could I force it to play in mono instead of it trying to play it in stereo?

Thanks,
-Matt

Whats the make/model of the soundcard you are using ?

I'm using the on-board sound from my motherboard. It's an Abit NF7-S.

Did the same problem happen in WMP10, before you upgraded to 11 ?

I just tried rolling back to 10 and it does the same thing, so yes.