Sound stops working in KDE after a few hours

[Marcelo]

Binary package hint: phonon-backend-gstreamer

KDE becomes mute after a few hours after the computer is turned on if using gstreamer as the backend for phonon. Generally sound stops working after 4-5 hours, but there have been occasions were it took as long as 2 days before failing. When sound fails, a reboot is needed to get it working in KDE again (note, however, that the problem affects only KDE events sounds and KDE applications - non-KDE applications like skype or mplayer still produce sounds without any problems).
Also, when I go to SystemSettings -> Multimedia after the sound stops working, I get a messaging informing that KDE has detected that one or more internal sound devices were removed (?!) and asking if KDE can permanently forget about them. The supposedly removed devices are:
Capture: HDA Intel (ALC275 Analog)
Output: HDA Intel (ALC275 Analog)
Output: HDA Intel (ALC275 Analog) #1

After a reboot, the devices magically hurry back inside the notebook and start working again.

Before Natty I was running Lucid in this very computer with no sound issues at all.
This happens after a clean Kubuntu 11.04 amd64 install and also happens if I first install Ubuntu 11.04 amd64 and add kubuntu-desktop later. Since Jaunty, I have always installed first Ubuntu and later added kubuntu-desktop, because I used to have similar sound problems when installing Kubuntu directly (with other computers, before I've bought this one) that seam to be solved this way. But now with Natty, the problems persist even if I install Ubuntu first.
This problem does not occur when using vlc as phonon backend. However, sounds are somewhat distorted when using this backend. Also, if KDE is already mute, changing the backend to phonon does not make sound work again. A reboot is still needed.

The notebook I'm using is a Sony VAIO VPCF111FB.

ProblemType: Bug
DistroRelease: Ubuntu 11.04
Package: phonon-backend-gstreamer 4:4.7.0really4.5.0-0ubuntu2.1
ProcVersionSignature: Ubuntu 2.6.38-8.42-generic 2.6.38.2
Uname: Linux 2.6.38-8-generic x86_64
NonfreeKernelModules: nvidia
Architecture: amd64
Date: Tue May 31 17:35:25 2011
InstallationMedia: Ubuntu 11.04 "Natty Narwhal" - Release amd64 (20110427.1)
ProcEnviron:
 LANGUAGE=pt_BR:pt:en
 PATH=(custom, user)
 LANG=pt_BR.UTF-8
 SHELL=/bin/bash
SourcePackage: phonon-backend-gstreamer
UpgradeStatus: No upgrade log present (probably fresh install)

[Harald Sitter (apachelogger)]

Thanks for taking the time to report this bug. 11.04 reached end of life on October 28, 2012.
Please see this document for currently supported Kubuntu releases:
https://wiki.kubuntu.org/Releases

Unfortunately this means that there will be no more bugfixes for 11.04. It is also recommended that you upgrade, if you have not already.

Please feel free to report any other bugs you may find, and thanks for your understanding.