The bug report was opened for natty and it seems that a grub-install fixes this for everyone and for later releases, too.
This seems to be an issue only after upgrades and is no real problem because the system continues to boot after a key press. grub-install also fixes this for me after jumping from 12.04 ( - 12.10 - 13.04 ) - 13.10. ** Changed in: grub2 (Ubuntu) Status: Confirmed => Invalid -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/733836 Title: "Error: file not found" when booting, then boots up anyway To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/grub2/+bug/733836/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs