I did a clean install of Windows 7 on 2 identical computers with the Asus P5AD2-E motherboard. Both have the same problem: a message "No Audio Output Device is Installed". Letting Windows try to solve the problem then results in an attempt to reinstall the device driver, which fails with the message "High Definition Audio Device has a driver problem". Nothing I tried so far (uninstalling the driver, manually installing a RealTek driver for Windows 7) has worked.
Any help is appreciated!