USB headset makes wobbling bass instead of sound

I have a Microsoft LX-3000, which is a USB headset. I can use it on other computers, but apparently mine doesn't like it, just on the software side, because the headset itself isn't broken. I can vaguely hear the correct sound coming out of it, but mostly all I get is a very loud, distorted & wobbling (it seems to oscillate rapidly across a range of pitches that just go all around the correct sound tone) bass-y noise that covers up anything useful that it's also playing.

My analog headset still works, but it's been developing left/right balance issues lately, which are entirely the fault of the hardware itself, not my computer.

I'm running Windows XP Home SP2 with .NET 3.0 architechture underneath it all (which has caused some weird problems in the past with .NET 1.1 I think, so I wouldn't put it past just .NET, though I doubt that's really it) and I'm running on an EVGA 680i motherboard just off the onboard sound.

Any ideas at all why a USB headset would do this sort of thing?