This is on Edgy right? I don't get that error while staring quodlibet. You could be right that problem is with python-gst0.10 package which provides python gstreamer bindings.
What's the output when you type on terminal: python import gst gst.registry_get_default().find_plugin("mad") ** Changed in: quodlibet (Ubuntu) Status: Unconfirmed => Needs Info -- Quod Libet won't start at all https://launchpad.net/bugs/59755 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs