I have this problem also. No takers on fixing it? Well, if there's someone who can help, please do as this issue is growing in popularity on the internet with no one to really fix it.
My system: HP Pavilion DV6604nr, running Vista 32 bit, Service Pack 2.
before this problem: Conexant High Definition Smart Audio HD2
Isssue: Lost sond output on internal speakers headphone jack.
Found "No Audio Output Device is installed" message when I mouse over the speaker icon which has a red X next to it.
Checked Playback and recording Devices - there were some listed, after rebooting, there are none listed in iether the Playback or Recording windows even with show Disabled and Show Disconnected Devices checked.
Rebooted - the driver installed during reboot and the sound worked for about 5 minutes, then went out. No rec X this time, but no sound.
Rebooted - Same issue I started withm - Red X, No playback devices showing.
Tried: resetting my bios to default settings and updating it. No change.
Tried: Downloading all previous and current versions of Conexant HD Audio drivers
from HP site and other sites. Conexant does not furnish the driver themselves.
Result: "Could Not find the MEDIA device for this driver" message occurrs each time I try to load the drivers.
Tried restoring to a point before the issue began, but no restore points avalable so went back to the oldest avalable - problem still exists.
Tried using HP Recovery Manager to install original driver - get same "can't find the Media device" error message as I did with the other drivers.
Ensured I have the latest Vista updates installed - the issue continues.
Any other ideas out there? Thanks.