Comment 6 for bug 353071

Have experienced the same problem here.
Upgraded from 8.10 to 9.04 beta (32bit), converted to ext4 and reinstalled grub as instructed.

Couple of days everything was fine. After updating yesterday though, I got the grub 24 error when booting the next time.

Traditional way of booting with the live cd and using grub to reinstall failed.
Then used the procedure described by Ralf above to reinstall using live cd and grub-install and now I can boot again.