Does anyone have Logitech z-540 speakers?

[Mojambo]

Hopefully you'll be able to understand my problem here.

I was just listening to some music in Winamp and realized that the sound was funky. I checked the balance and found that there was no sound on the left. Now I know it's not a problem with that particular speaker because when I swap out the connection for a different one there is no sound out of that one.

I don't think it's a sound card issue because when I plug in headphones I get stereo sound.

I'm completely stumped. I've had these speakers forever and never have had this problem before.

Any ideas? Does anyone have these speakers? How do you have them hooked up?