Is nautilus-cd-burner installed? If you did an upgrade, you may have"which nautilus-cd-burner" shows it to be in /usr/bin; invoking it directly gives a complaint about a NULL handle returned from /usr/lib/gnome-vfs-2.0/modules/libmapping.so and a "No files selected" popup that says that any files to be written must be copied to the burn:/// location.
needed to select it manually.
James