Background:

A clean install of Windows Vista SP1 is attempted on an hp Pavilion dv1603tn.  The "high definition audio device" shows failure in Device Manager.  The HP provided Vista package was installed.  The "High Definition Audio Device" device error goes away, but the resultant "Conexant High Definition Audio" device is silent and refuses to play any sounds.  Attempts to do so show sounds appearing in the sound mixer - the levels change - but nothing comes out the main system speakers.

Solution:

The HP provided Vista package is non-functional.  Download and install the "XP" driver package on their website.  Windows Update then will provide an updated driver package for Vista if necessary.

XP package installed: Release Date: 2006-05-15           Version: 3.21.0.0 A
Vista package attempted: Release Date: 2007-05-15           Version: 3.38.0.50 A
It is possible that an "updated" package will be released in the future by the manufacturer to correct this problem.

1. Download the XP driver package, and open it with WinRAR or 7-zip or a similar archiver, and extract it's contents.  (This will prevent the package from auto installing.)
2. Next, right click on the High Definition Audio Device in Device Manager and update the driver to this package, by pointing the wizard to the folder where the files were extracted it.

The functional driver with Vista SP1 has a date of "4/18/2006" and is version "3.21.0.0".

Note:

Ensure also you download and install the latest video and chipset drivers from Intel.com - NOT HP's support website, which shows releases several builds behind.