hi
if you haven't let every new distro to install a new bootloader and you have not a partition dedicated to /boot
it should be something like that:
Code:
#boot=/dev/hda
default=0
timeout=10
splashimage=(hd0,0)/boot/grub/splash.xpm.gz
title Fedora Core (2.6.x-x.xxx)
root (hd0,0)
kernel /boot/vmlinuz-2.6.x-x.xxx ro root=LABEL=/ rhgb quiet
initrd /boot/initrd-2.6.x-x.xxx.img
title DSL Distro (2.y.y-y.yyy)
root (hd0,4)
kernel /boot/vmlinuz-2.y.y-y.yyy ro root=LABEL=/ rhgb quiet
initrd /boot/initrd-2.y.y-y.yyy.img
title Slackware Distro (2.z.z-z.zzz)
root (hd1,0)
kernel /boot/vmlinuz-2.z.z-z.zzz ro root=LABEL=/ rhgb quiet
initrd /boot/initrd-2.z.z-z.zzz.img
title Phlak Distro (2.v.v-v.vvv)
root (hd1,4)
kernel /boot/vmlinuz-2.v.v-v.vvv ro root=LABEL=/ rhgb quiet
initrd /boot/initrd-2.v.v-v.vvv.img
where x,y,z,v are the appropriate numbers from its distro
in anycase you may post your grub.conf and we will try to fix it.