I have a Plantronics .Audio 626 DSP headset. My headset is recognized by Windows 7, but my mic does not pick up sound. I've tried unplugging it, plugging it back in, restarting my computer, messing with drivers (all of my drivers are up to date), messing with sound settings. I've had my headset for a about 2 years, and it's gone through quite a bit of punishment. Any ideas?