sound problem

[Markus Lutzer]

I have a laptop with an internal Intel ICH6 audio device. It worked
quite well with Ubuntu Breezy. With Dapper, some applications are able
to use the sound device, some don't. For instance, the old skype (OSS
based) worked, the new one (ALSA based) don't, Audacious (ALSA output)
does, system sounds don't. In system -> preferences -> audio my sound
device is selected but pressing on a play button don't have any affect.
How can I figure out why system sounds don't work?