My New MSI Mobo Will Not Speak Up!

Question

I just replaced the motherboard in my computer with a new MSI P4M900M2-L motherboard (VIA Chipset). I did a "repair" install of Windows, re-activated it, and everything in the system is now working fine except...the integrated sound function on the mobo does not work. I've downloaded and successfully installed all recommended drivers from MSI website using "Live Update Online" feature. Also downloaded and ran MSI InfoView XP utility. All looks good on this utility except the SOUND tab which says "Sound Card Not Detected!". The Windows Device Manager shows an "Audio Device on High Definition Audio Bus" but its properties sheet says "No Drivers are installed for this device". If you click on the "Update Driver..." button on the Properties "Driver" tab, nothing at all happens. All the Driver info on this tab shows either "Not Available" or "Unknown".
I connected the motherboard on a non-conducting surface outside the case. Same result; MSI InfoView utility reports "Sound Card Not Detected". I have also verified that the MB mounting holes line up correctly with the case mounting standoffs - no shorts.
On advice from MSI support, I RMA returned the board to the vendor and they sent me a new one - same model, P4M900M2. I installed the new one and...same problem! Everything else works perfectly. I went through the process again of updating drivers using MSI's Live Update Online. It scanned my system and said all drivers were up-to-date. I loaded the CD-ROM that came with the mobo and clicked on the RealTek Driver button, but nothing at all happened. I browsed the CD and in the "Sound" folder found two setups - one for VIA HD and one for RealTek. Tried running the RealTek setup; it went partway through and then said "Install Realtek HD Audio Driver Failure!!". (Thanks for all the useful info!) Then tried the VIA HD setup. It ran a bit & then said "ERROR - We can't find HD audio device". So nothing worked.
It seems quite unlikely that I received two defective motherboards in a row, each with the exact same defect !!?? Seems like there must be some driver or setting or jumper or something that's preventing the sound function from being recognized. Does anyone have any ideas? Thanks.

Answer 1

Joy! My problem is solved. I received the following from MSI Technical Support (it took them two tries, unfortunately; first they concluded that the motherboard was bad and told me to RMA it, which I did; only to have exact same problem with 2nd board.) Anyway, this solution worked like a charm. The key, apparently, is deleting that Microsoft UAA HD Audio driver under System Devices.
Hope this info may help some other poor soul out there fighting the same problem.
Thanks to Bosskiller and Del UK for all the suggestions.
Here's what tech support sent:
Be sure the Microsoft HD UAA patch has been applied: http://support.microsoft.com/kb/888111/en-us ** The Microsoft HD UAA device drivers interfere with the Realtek drivers and prevent them from loading. The cure is to 1) Open the control panel and launch System 2) Click on the Hardware tab and then launch the Device manager. 3) Go to the bottom and click on System Devices 4) Look for Microsoft UAA HD Audio driver. 5) Right mouse click on it and first disable the driver, and then unload it. 6) Reboot the machine. 7) There should be no problem now with loading the HD audio drivers. Please check and be sure the bios setup has the on board audio setting been set to enable or Auto. Please have all on board audio header removed from any case front audio or other adapter connections and only connect the speaker/headset to the rear audio output port (green) and retest. Please test out the mb and components outside the case with mb box to support the board. This can prevent any short or grounding problem to the mb which can cause audio to stop working as well.