Rhythmbox Play/Pause button not working correctly

Binary package hint: rhythmbox

Ubuntu 10.10 32bit standard live CD used to install system on a Dell Studio Laptop 1555.

Rhythmbox Play/Pause button not working correctly, in both "mini" (from main Gnome bar sound icon) and main Rhythmbox GUI window, and with laptop hot-key
Play/pause, worked correctly in Totem Movie Player (v2.32.0), both the button in the Totem GUI and the laptop play/pause hot-key.

If you open Rhythmbox, and select a track. You can start the track playing using one of the play buttons, main/mini/hotkey, but after that pressing any one of the play/pause buttons does not pause the track. If you quit from the Rhythmbox you can then repeat (ie start a track using one of the play buttons).

Note that pressing the "pause" icon in the GUI causes the button to change to a "Play" button, but the track continues playing. If the "Play" button is now pressed nothing changes, ie it remains as a "Play" button.
If you quit from Rhythmbox, re-start Rhythmbox, this behaviour can be repeated. The same is seen if you press the "mini" player "Pause" icon once a track is playing.

Suspect (guess) that this issue started after installing the "unity" (netbook) window manager? I cannot be sure as I have also installed the various updates that have been available. The issue above is occuring with the standard Gnome window manager. The same behaviour also occurs if I use the netbook window manager.
To confirm that the play/pause buttons had worked previously booted up using standard Gnome 10.10 32bit live CD. Rhythmbox play/pause and laptop hotkey buttons worked corrected.

Other buttons (ie the previous and next track) work correctly both in the main GUI, mini player, and using the laptop hotkeys.

$ apt-cache policy rhythmbox
rhythmbox:
  Installed: 0.13.1-0ubuntu6
  Candidate: 0.13.1-0ubuntu6
  Version table:
 *** 0.13.1-0ubuntu6 0
        500 http://gb.archive.ubuntu.com/ubuntu/ maverick-updates/main i386 Packages
        100 /var/lib/dpkg/status
     0.13.1-0ubuntu5 0
        500 http://gb.archive.ubuntu.com/ubuntu/ maverick/main i386 Packages

ProblemType: Bug
DistroRelease: Ubuntu 10.10
Package: rhythmbox 0.13.1-0ubuntu6
ProcVersionSignature: Ubuntu 2.6.35-24.42-generic-pae 2.6.35.8
Uname: Linux 2.6.35-24-generic-pae i686
Architecture: i386
Date: Mon Jan 3 12:25:40 2011
EcryptfsInUse: Yes
InstallationMedia: Ubuntu 10.10 "Maverick Meerkat" - Release i386 (20101007)
ProcEnviron:
 PATH=(custom, user)
 LANG=en_GB.utf8
 SHELL=/bin/bash
SourcePackage: rhythmbox