7.04's rhythmbox is built against gstreamer 0.10. please try installing the nessesary 0.10 plugin for aac.
-- Rhythmbox cannot handle AAC files with gstreamer faad plugin https://launchpad.net/bugs/81958 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs