Thanks, Miguel 99
Had the same problem with my ASUS 5PKR board. After a new installation of Windows XP Pro including an upgrade to SP3, the sound dissapeared and installation of the audio driver was impossible, showing the famous error code 0xE0000227 message. Even the installation of a Creative Soundblaster card did not work. All suggestions, found on other sites did not work. But after following your advise it worked out at the end. Some remarks: After finding the Microsoft UAA HD bus driver under the System Devices part, I had to disable it first (deletion was not allowed), installed the latest Realtek driver, found on the Realtek site and restarted the computer.
After that, deletion of the UAA driver was possible. A new installation of the Realtek driver was needed, but after doing this and again a restart, the sound was there.
But your adviose was a great help. Don't know, who is to blame (I however suspect mr. Gates' company, since the problem occurs with a lot of motherboards)