Installing Arch--bootloader killed my Grub

I have gentoo on my machine and I want to give arch a try. I used parted to adjust my partitions. Before installing anything, I rebooted to make sure that gentoo still worked and it did. So I went ahead and installed arch. I thought I did the right thing in not installing the bootloader because I already had grub on the mbr. SO i rebooted. and all I get is a screen full of "grub grub grub grub grub grub etc."

I'm not at home so I can't fix it right now, but this is what I think I should try. Using the gentoo live cd, I can get into the system, mount everything, and chroot into it. SHould things be okay if I re-emerge grub, reset it up on the mbr, and then edit my grub file to the arch partition. Does this sound like the right process, or am I missing something?

Okay, it didn't work. here's what I tried:

Booted live cd

mounted /, /boot, and /proc
chroot /mnt/gentoo /bin/bash

I unmerged grub, then reinstalled it:
emerge -C grub
emerge grub

then setup grub on my mbr:
root (hd0,0)
setup (hd0)
quit

exited, umounted, and rebooted. Grub still does not load. I just get a repeated "GRUB" over the entire screen and the processor light goes bonkers. Can anyone help me please?

Still no luck. I've deleted the arch linux partitions, and used a live cd to uninstall grub and reinstall it. I've tried different versions, and it just won't work. Does anybody have any suggestions?

cheat. I have usually installed lilo when it happens, after updating the /etc/lilo.conf with some cut-n-pasting and tweaks.

Then until the next time you update the kernel just use lilo--who cares as long as it boots?

The missing commands to use are the "mount", "swapon", and "cp" command, use RIP or rescue.

After booting (and then mounting the system "/" to /mnt/sysimage if the rescue disk doesn't do it for you) then make sure all of the respective portions of the grub installer are present in the /etc in ram--this is the system you are running. If they are not there, cp them.

Use mount to mount your real /boot (either on /mnt/sysimage/boot or label=/boot for a partition) over the existing /boot directory in ram--the "rescue-/boot".

Now, when you reference your "real" /boot when running the grub commands you are giving the correct locations for grub stage 1.5 and stage 2 plus the correct reference to "boot.b" for the installer to write into the MBR--via the variable/expression/test pre-processing for commands built into the shell.

Got it?

The reason I use lilo is that the only syntax I have to remember in that of the /etc/lilo.conf file. Otherwise, the process is identical.

Wow--great info, thanks. However, I have no idea what you're talking about with regards to copying grub onto the ram /etc and all that business. If you could explain that a little more specifically I'd really appreciate it. Thanks so much.