Booting the liveCD and trying to rightclick/umount the CD give the above error. This should probably give a different error.
I've added a hack to fix this; needs a fix in HAL but this bug never occurs in real life where all but rootfs, system fs's are mounted by the desktop anyway. http://gitweb.freedesktop.org/?p=users/david/pilgrim.git;a=commitdiff;h=c8a8fa23bfafdfa23d513f28186af145e340fc39 Confirmed to work in latest livecd build.