When i was under Dapper, i had the same problem : all the new linux- image installed but booting on the old (given with the installation), and impossible to boot on the newest (with yaboot, it is automatic normally).
-- booting obsolete kernel https://launchpad.net/bugs/67549 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs