no sound when playing iplayer etc

Can play sound on log on and music files
 But no sound in iplayer or other web sites
Well sometimes it works but not often

ProblemType: Bug
Architecture: i386
Date: Tue Feb 23 07:45:22 2010
DistroRelease: Ubuntu 9.10
ExecutablePath: /usr/bin/kdeinit4
InstallationMedia: Kubuntu 9.10 "Karmic Koala" - Release i386 (20091028.5)
Package: kdelibs-bin 4:4.3.2-0ubuntu7.2
ProcEnviron:
 LANG=en_GB.UTF-8
 SHELL=/bin/bash
ProcVersionSignature: Ubuntu 2.6.31-19.56-generic
SourcePackage: kde4libs
Uname: Linux 2.6.31-19-generic i686