do you still get this issue ? could you provide some details on your system,
gstreamer/gst-plugins versions ?

I recently tried again and I still get this problem (though I thought this issue
was solved before that):

System is debian unstable/experimental (to get gnome 2.10). Stuttering seems to
be not CPU related but only when slow media is used, e.g. a samba share over a
wireless network. Thus the issue is buffering. Rhythmbox should try to keep the
cache always filled to a maximum. When using mplayer/xmms to play the same mp3's
the problem does not happen at all.

Thanks for the bug report. Unfortunately, that stack trace is not very useful in
determining the cause of the crash. Can you get us one with debugging symbols?
Please see http://live.gnome.org/GettingTraces for more information on how to do so.

Sorry, but I don't understand, rhythmbox is not crashing, but just the sound is
stuttering...

I've commented on the wrong bug, thanks for noticing.

hmm isn't this rather a gstreamer/gnome-vfs problem or does RB set the buffer 
size(s) and/or timing parameters?

actually, *I* won't expect any pre-buffering from a vfs, but only from an
application that needs it, i.e. rhythmbox should buffer say 1 MB then start
playing and always try to keep that buffer filled to the maximum. In the case
gnome-vfs supplies a pre-buffered-read function it is a bug in gnome-vfs... note
however that all the other apps like xmms/mplayer try hard to do the
pre-buffering  as described above on their own.

I notice this also. I hope there is something that can be done on this :)

Marking all buffering-related bugs as duplicates of #172389, even though they don't all request the same behaviour.  Any attempt at fixing these problems will have to address them all.

*** This bug has been marked as a duplicate of 172389 ***