Horrible high pitched noise from iSight mic only under OSX My old 2008 Macbook's iSight microphone is acting up but only under OSX. In bootcamp running Windows XP, it's fine!

The problem is a high pitched sound, very reminiscent of old radios with the pitch going up and down. 


It happens regardless of the app I use
Rebooting OSX did not make a difference. 
Adjusting the mic volume does not help.
Turning ambient noise reduction off does not help.
CPU is idle and fans at 3200rpms, same as Windows XP
I've not changed any audio settings or loaded any audio software
It's happening while using headphones so it's not a feedback loop


Windows XP does NOT have this high pitched noise, just the normal background noise and it is usable. 

Any ideas?

PS: Not that I think it's relevant but I'm running Snow Leopard.
It's quite old question but I had same problem with two USB cameras just few days ago. To fix it go to the MIDI setup (i.e. by Spotlight Search Bar). On the left side choose your USB microphone (USB camera) and on the right try to change frequency to 44 100Hz and format 16-bit. Previously I had 24-bit which causes the problem.