I have a Dell Inspiron 1720 laptop with Windows Vista (32-bit operating system). The laptop has a built-in microphone siding (two vertical slits on the left of the webcam), but I can not use it. Even an external microphone does not work. I read on various forums it must be activated, but I have found no forum telling me how. How can I fix this problem? Any help regarding this topic is appreciated. Thank you.