Hi all. After a week with this problem, Audio Windows service that won't start and to avoid the Microsoft support advice: reinstall XP, then re update with Vista Ultimate...

Here was my case : Audio windows service dont start because another one don't either : the Audio End point Builder (AudioEndpointBuilder) with 998 error ?!
Many solutions found didn't work, then I tried another one given for another sound problem, and it worked for me :

- copy the file audiosvr.dll from another Vista PC (not especially Ultimate)
- paste it on one of your drive ex: D:\
- Boot/Start with Vista dvd
- Choose the "Repar" option
- Than choose the "Command Line" option
- To type "copy d:\audiosrv.dll c:\windows\system32\audiosrv.dll"
- Restart !

If only i could save you from a all reinstallation... Hope this helps !