I have a Dell laptop E1705 with the Sigma Tel High Definition Codec sound card.

Here are some details found in a txt file for the audio card
Title : Audio: SIGMATEL STAC 92XX C-Major HD Audio Driver
Version : A02
OEM Name : SIGMATEL
OEM Ver : 6.10.0.5343

Everything was working fine untill I got some updates. After I updated, my
microphone stopped working. I re-installed the drivers I got from dell's
website and everything was fine again. But it seems at random intervals,
Vista tries to "update" the driver again and my mic stops working. Everytime
this happens I have to re-install the old driver to get things working again.
I finally told Windows to ask me before installing any updates. From looking
at the forums, a lot of other people are having problems with the sigma tel
drivers after an update.



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