Question : Problem: audio works during login sound but not afterwards

I just built a new computer based on the Intel DX48BT2 motherboard, which has a Sigmatel onboard HD audio system.  I have had some interesting trouble with this:

After installing Windows, I loaded the Intel driver disc which included the Sigmatel drivers; sound worked during login (not sure after that, wasn't paying attention.)  Windows Update replaced the driver with a new one; then, audio stopped working entirely.  I unloaded that driver and replaced it with the Intel-provided one, audio started working again.  However, it only works during the login startup sound, and then stops after that!!

There is also an audio device as part of the ATI HDMI video card; I have disabled that.

Windows Audio and Sigmatel Audio services are both started.

When I play a sound manually, the computer acts like it is playing successfully - no "no audio device" message or anything.

I have tried installing the Universal Audio Architecture driver as well (KB888111), no dice.

I have used MSConfig to remove all unnecessary services/programs that I can think of.

Any ideas?  What would allow it to work consistently when logging in, but not after that?

Answer : Problem: audio works during login sound but not afterwards

i have 3 schools of thinking
1) when the machine boots it uses standard audio and then switches to hd (coaxial/optical)
2) the machine thinks the driver is installed but is not complete.like the Sigmatel 9274D audio codec
3 )this system board has 5 analog audio output and it swops after boot

i think for that sound card you also needs UAA kb835221
check you has installed the full chipset driver

hope this helps
i will do more checking