Latitude External mic not working

My Latitude D-820 does not seem to recognize an external mic.    When I plug in a microphone I get no pop up asking if I want to use it and the Recording Control panel does not automatically  switch to "Microphone" (versus Intermal Microphone).  If I select Microphone on the recording control panel and try to use it I get silence.   I have tried multiple microphones.    This used to work and has suddenly quit.  I have the current SigmaTel drivers.  Pop ups are enabled on the Sigmatel control panel.  I have tried every combination I can think of on the Recording control panel to get this to work and still all I get is silence.

The last time I got it to work, I had the microphone connected and rebooted and it worked.  I have tried that several times now to no avail.  The laptop is in a docking station if that might make any difference.

The internal mic works fine, but since it is in a docking station, it not very usable.

If anyone has any ideas, I would appreciate the help.

Thanks,

Doug