I recently reformated my dell XPS 1530. I have reinstalled the sigmatel audio codec drivers off the driver download page. The sound works fine, and the build in Microphone works (though it sounds terrible). When I plug in an external microphone the sigmatel pop-up comes up just like it used to, and I can select microphone.
After I do though, there is no input from the microphone. The compute regonizes it, but nothing comes through. It still defaults to the build in mic on programs such as sound recorder and online games. When i force the external mic to be the default input device it not only still doesnt work, but I lose all sound until I restart. I have reinstalled the drivers many times. I did not have this problem before the reformat and I have no idea what is wrong.