Comment 1 for bug 1052162

@JoeBaloney: Thank you for this bug report! :)

Which version of the dock are you using? With which music player?
I think I already fixed a bug about this kind of problem (there was a problem with Amarok) and there were a bug with Pithos (http://www.glx-dock.org/bg_topic.php?t=6438 and bug #1039272 ).

I don't have this bug with Rhythmbox and Clementine. It can be interesting to get some useful messages in order to know if there is a bug with the dock or the player.
Can you launch the dock with this command and post here all messages that you'll have when a new song is starting to play:
  $ cairo-dock -l debug --colors | sed -n "/musicPlayer\// {N;p;}"

Can you also launch this command (the dock has to be started before):
  $ dbus-monitor > ~/dbus-monitor.log
Then change the song (if possible a new artist and a new album) and press 'Ctrl+C' on the terminal. Then post the content of the 'dbus-monitor.log' file here.

Have fun ;)