Okay. I just compiled a new kernel, version 2.4.22smp on a RH9 system. Before this, I had 3 options in my grub menu, all of which are standard RH9 kernels.
I downloaded the source, ran the following:
#make xconfig
#make dep
#make bzImage
#make modules
#make modules_install

I also ran the mkinitrd command.
Here is my grub menu.1st file:
# grub.conf generated by anaconda
#
# Note that you do not have to rerun grub after making changes to this file
# NOTICE: You have a /boot partition. This means that
# all kernel and initrd paths are relative to /boot/, eg.
# root (hd0,0)
# kernel /vmlinuz-version ro root=/dev/hda3
# initrd /initrd-version.img
#boot=/dev/hda
default=0
timeout=10
splashimage=(hd0,0)/grub/splash.xpm.gz
title Red Hat Linux (2.4.22smp custom)
root (hd0,0)
kernel /vmlinuz-2.4.22smpcustom ro root=LABEL=/ hdc=ide-scsi hdd=ide-scsi
initrd /initrd-initrd-2.4.22smpcuston.img
title Red Hat Linux (2.4.20-20.9smp)
root (hd0,0)
kernel /vmlinuz-2.4.20-20.9smp ro root=LABEL=/ hdc=ide-scsi hdd=ide-scsi
initrd /initrd-2.4.20-20.9smp.img
title Red Hat Linux (2.4.20-8smp)
root (hd0,0)
kernel /vmlinuz-2.4.20-8smp ro root=LABEL=/ hdc=ide-scsi hdd=ide-scsi
initrd /initrd-2.4.20-8smp.img
title Red Hat Linux-up (2.4.20-8)
root (hd0,0)
kernel /vmlinuz-2.4.20-8 ro root=LABEL=/ hdc=ide-scsi hdd=ide-scsi
initrd /initrd-2.4.20-8.img


I get error 13 (invalid or unsupported executable) at startup when I try to boot my new kernel. I have played around with my bios settings for the hard drive (from Auto to LBA etc), however I get the same error. Any suggestions? thanks in advance.

--Johnnyd

Are you absolutely sure you copied the kernel from arch/i386/bzImage to the file you specified? That has happened to me more than once.
Also, I have noticed xconfig is unreliable (When I tried it, it only gave me about half of the options). I noticed you use the root=LABEL option. I have never gotten this to work in a kernel that I have compiled myself. Doesn't sound like the problem you specified, but you could run into it further along.

Yes, I am certain i copied the file.