Soundmax Audio on HP NW8440 stopped working

Hi,

Recently installed Vista Business x64 on a HP NW-8440, sound worked fine to
start with. Somewhere along the (subsequent programs) installation way, the
sound went missing.

Tried to go back with uninstallations, system restore, didn't help, tried
diagnosing the device on HP's homepage, and it says the device is not
functional. It looks ok (no conflicts, device operational) in device manager,
tried to install, reinstall et.c. Tried Microsofts Vista RTM and the official
HP/Analog soundmax driver without luck.

When playing video in WMP 11, it stops after three seconds with details
leading to a Access denied error. When the sound worked, the video in WMP 11
worked as well.

How do I troubleshoot the device driver load and find out what the issue is?

brgds / Niklas