Odd Sound Issue

Hello Tom'sHardware community,

I've come across an issue with my case's front panel audio jacks, and was hoping for some ideas as to what might be going on. In the past, the headphone jack has worked just fine - but now when I plug my headphones in, no sound comes through. To eliminate some questions that you guys might ask:

1) MOBO: ASUS M4A79XTD EVO, Case: Lancool PC-K62, No sound card, Win 7 64 bit
2) The problem arose when I had no sound driver / management software installed, so I installed the latest VIA control panel off the ASUS site for my mobo and the problem persisted
3) The headphones work when plugged into the back panel / in any other audio device, and no other headphone works in the front panel either

Here's the strange part - when plugging the headphones in, the VIA panel recognizes that they've been plugged in with a little pop up box asking to confirm that headphones have been plugged in, and then graphically indicates that the connection is live (as well as muting the speakers). Additionally, in Control Panel \ Sound, audio is clearly outputting (the little green bars are lighting up as normal). In other words, it LOOKS like everything is working - but nothing comes out of the headphones!

My question is this: is there anything that I can do to get my front panel working? Have you heard of this kind of problem happening before? What, in short, should I do?

I thank you all greatly for spending the time to read this, and eagerly await your responses.