Microsoft Expressions Screen capture Audio Problems

I'm using Microsoft Expressions Screen capture 4.0.4276.0.   When I record my voice on screen capture an import the file to the encoder (before I encode) the audio level dips very low and then come back up about every 5 sec.  I have tried a different mic and have the same issue.  At one point (about a month ago) there was a very clear recording but I don't know how I got it.  I checked all the audio settings (bit rate etc) and they seem to be identical.  Any help would be appreciated.