To me, that sounds like grub. If that happens, here is what I usually do.
Where x is disc number starting from 0, and y is partition number starting from 0.
kernel image is usually vmlinuz-[something-or-other]
initrd is initrd-[something-or-other].img
For me, the [somethng-or-other] is the output of `uname -r'
Be sure to record the commands, so that if they work, you can insert them into /boot/grub/menu.lst