Windows 7 - Built-in Webcam Microphone and Microphone Line-in Not Working

I have a Dell Vostro 1500, running 32-bit Windows 7. It came with Vista, but I upgraded to Windows 7 a couple months ago, which I think is causing the issues I'm experiencing. According to whoever I'm speaking with, the sound for the microphone built in to my webcam fades in and out and gets really loud randomly. In an attempt to solve this, I bought an external microphone which also does not work.

The sound driver is the SigmaTel High Definition Audio CODEC, version 6.10.0.5614. When I tried to update it through Windows 7's update driver software it says I have the best version for my system, but I still suspect that this could be what is causing the problem. I can't seem to find a better driver though.

Any ideas?

Thank you

Got the same problem with a Dell Vostro 1500 microphone line-in not working. I can't help I'm afraid; I am just posting here so I get notified of any responses.