I have had grub fail to install with Intrepid on multiple different install attempts. The installation from the Live CD fails to give an error message at all. The installation from the alternate install states that the grub installation has failed. (LILO fails as well.)
It is possible to complete the installation without a boot loader. It is then necessary to boot with a grub floppy (or media of your choice), and manually boot into the installation,
At this point I discovered that the grub package had been installed, but none of the post-installation processing had occurred. There was no /boot/grub directory. It is necessary to run:
(update automagic options in menu.lst using editor of your choice)
The machine was able to boot normally at this point.