I commented on a similar bug - 330298, but probably should have commented here, since it is closer to my own situation.
I had exactly the same issue with NVidia soft RAID with a RAID1 pair.
Got the same message you got.
Realised I was still booting from kernel 2.6.27-14, but that I now also had 2.6.28-12. Asked grub to boot from 2.6.28-12 and it booted fine.
Which kernel are you using?
I commented on a similar bug - 330298, but probably should have commented here, since it is closer to my own situation.
I had exactly the same issue with NVidia soft RAID with a RAID1 pair.
Got the same message you got.
Realised I was still booting from kernel 2.6.27-14, but that I now also had 2.6.28-12. Asked grub to boot from 2.6.28-12 and it booted fine.
Which kernel are you using?