Sound doesn't work with Iceweasel open

["Goudar Vishwanathappa Manu" <manu.gvm@gmail.com>]

hello,
Whenever Iceweasel is open, when I play songs I don't get any sound
output. If I go to System>Preferences>Sound and press test, a window
pops up saying
"audiotestsrc wave=sine freq=512 ! audioconvert ! audioresample !
gconfaudiosink: Internal GStreamer error: state change failed.  Please
file a bug at http://bugzilla.gnome.org/enter_bug.cgi?product=GStreamer.";
I am using the lenny/testing. I have removed totem-xine and have
totem-gstreamer installed and Iceweasel uses mplayer-plugin for
streaming videos over internet.
Anyone has any idea or suggestions about how can I avoid this problem?

Regards
--
G V Manu