This is known issue. All you have to do is pass correct option to grub boot loader while booting so it can mount file system and boot into a kernel. You need to modify line called root (hdX,Y).
When you see Grub boot loader hit esc key
- Select the kernel
- Press the e key to edit the entry root(hdX,Y)
- Press the e key to edit kernel entry
- Press ENTER key
- Now press the b key to boot
You may have to try root(hd1,0) for first slave, partition 0 and so on. Play little bit till you get success such as root(hd0,1), root(hd1,1) etc. See
GNU GRUB Manual 0.97
Once booted successfully update your grub.conf with correct root(hdX,y) entry.