[Karmic] conflicting audio after switching between users

Binary package hint: pulseaudio

Steps to reproduce the bugs:
1. Create 2 new users, user1 and user2 (to be sure you use Karmic default settings).
2. Restart. Login as one user, then double click on /usr/share/example-content/Aesop'\''s_Fables,_Volume_1_(Fable_1)_-_The_Fox_and_The_Grapes.spx
3. Switch to second user. The sound from the first user is still playing uninterrupted, even at gdm stage.
2. As the second user, double click on /usr/share/example-content/Ubuntu_Free_Culture_Showcase/SpiritOfUbuntu.ogv while the first user audio is still not finished.

Result: First user prevent any sound to be played as second user (with Totem, the video even doesn't start, but with other applications you can sometimes get the video but no audio). When the first user audio finishes to play, audio can be played as user2, but that would block audio for user1 if you switch back to its session.

Expected behavior: like in Jaunty and previous releases, sound from one user should stop playing when another session is active. In Jaunty and earlier, even VT had sound from one user when logged as this user, and from the other when logged as him.

Some audio applications on one session also prevent any sound to be played for the other user session even when they have nothing to play.

ProblemType: Bug
Architecture: i386
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: user2 2356 F.... pulseaudio
Card0.Amixer.info:
 Card hw:0 'Intel'/'HDA Intel at 0xf8100000 irq 22'
   Mixer name : 'Realtek ALC889A'
   Components : 'HDA:10ec0885,1458a002,00100101'
   Controls : 38
   Simple ctrls : 21
Date: Mon Sep 28 12:21:35 2009
DistroRelease: Ubuntu 9.10
NonfreeKernelModules: nvidia
Package: pulseaudio 1:0.9.18-0ubuntu3
ProcEnviron:
 LANG=en_US.UTF-8
 SHELL=/bin/bash
ProcVersionSignature: Ubuntu 2.6.31-11.36-generic
SourcePackage: pulseaudio
Uname: Linux 2.6.31-11-generic i686