Noise on the mic input of my Logitech webcam - worked great before

Hi everyone, this is my first post so be gentle. I have a 2009 Mac mini with Snow Leopard. I have a Logitech C110 camera that is plugged in via USB and shows up in the System Profiler just fine.

I used to use it for Skype video / audio calls but recently there has been a lot of audio interference from it. First thing I tried was using it on another computer - it worked fine with no noise at all so I can only conclude that there is something screwy with the sound interface on my mac. I've reset the SMC and PRAM - no luck.

You can see in 'input' the input level is at the max - I recorded a sample and it's just white noise. So I'm getting pretty confused. Is there any way to reset the sound / webcam drivers in OSX?