Do u have a seperate /boot partn?if true,there may be chance that u got grub installed to ur /boot dir on / root partn instead of /boot partition.also ur /etc/fstab shud be checked.post here.
again scrutinize ur /boot/grub/menu.lst groot= entry
## default grub root device
## e.g. groot=(hd0,0)
# groot=(hd0,8 )
^mine.i got a seperate /boot partn @/dev/sda9 so in grub (hd0,8 )
u know that
onlything u can check is that ur hdd is detected correctly by looking at /boot/grub/device.map for correct entries of ur hdds.
for eg; mine got:
there.for multiple hdd i think u know how to enter then.
another problem somewhere i read was grub got problem in reading partn entered as uuid's and LABEL's instead of direct name.although blkid command can show the o/p.
edit:all ur manual edits in menu.lst must not be btwn:
### BEGIN AUTOMAGIC KERNELS LIST
and
### END DEBIAN AUTOMAGIC KERNELS LIST
else they are over written !!!