GRUB booting from RAID1 is broken after Ubuntu update: how to recover?

[Andi Meier]

After updating Ubuntu Karmic (9.10) to Ubuntu Lucid (10.4), the PC does not 
boot anymore. Instead, it gets stuck printing:

  GRUB loading.
  error: the symbol 'grub_puts_' not found
  grub rescue>

Before updating, all was well. Although it is pretty obvious that the Ubuntu 
update created the problem, I did not receive any help. Since
the problem seems to be very related to GRUB, I'm hoping that you can give me 
some hints.

The following procedure works for me:
- booting from USB stick (ubuntu-rescue-remix-10-04.iso) into a prompt
- manually assembling the RAID array using:
    mdadm --assemble /dev/md0 /dev/hda1 /dev/hdb1
    mount /dev/md0 /data
- Et voila, I can access my hard disks now mounted on /data

What I am trying to solve now is: how can I configure the boot process (IOW: 
grub) so that GRUB is able to boot from RAID1 on /dev/hda1 and
/dev/hdb1 ?

This is an excerpt from grub.cfg which should define the menu entry for booting 
the Ubuntu Lucid:

menuentry 'Ubuntu, with Linux 2.6.32-22-server' --class ubuntu --class 
gnu-linux --class gnu --class os {
        recordfail
        insmod raid
        insmod mdraid
        insmod ext2
        set root='(md0)'
        search --no-floppy --fs-uuid --set f8a298fc-8551-4bcf-9b1d-cbaa062da2db
        linux   /boot/vmlinuz-2.6.32-22-server 
root=UUID=f8a298fc-8551-4bcf-9b1d-cbaa062da2db ro   quiet splash
        initrd  /boot/initrd.img-2.6.32-22-server
}


Could someone give me a hint what to do?

Many thanx in advance,
Andi