stupid question, have you unchecked the usually checked "mute" button in your audio mixer panel?
I am having problems with my microphone, I can hear sound coming from the speakers, however, when I try to use my mic (record or on the web), I can't. I have tried to use the sound trouble shooter, but it doesn't help because I can't use the mic. I have also changed mics and tested both mics on other pc's.

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