Hi, in Avast version 5.05.507 completely disappeared Windows System sound (startup, close program, shutdown…) through external sound card Audigy2, sounds only on-board beeper.
But if check the box - Settings/Troubleshooting/Load Avast services only after other system services,sound card starts to work again
My configuration: Avast Antivirus+ Comodo Firewall+ Win XP Pro Sp3 +Audigy 2+Realtek on-board codec
SJ, with best regards!