Linux redhat 4 boots into grub prompt.

[RR]

Did you try rebooting with the rescue CD or in the rescue mode with
the install CD and it found your linux install and mount it as
/mnt/sysimage? If it can't, then you got bigger problems. If it does
then you might wanna copy the /boot directory from a similar system
and try again. I'm sorry I've very limited in my understanding of how
all this works. I had a lot of issues in the past and somehow managed
to resolve them which is why i even know this much but might not be
enough to solve all grub related issues. Sorry.