Broken GRUB! How to fix?

[Alan Dayley]

I am writing this via Knoppix.  Great thing that!  Now, to the problem.

I have a dual boot system with Windows 2000 and Red Hat Linux 9.0.  Last 
night, after playing some games with my kids and burning CDs on a borrowed 
USB burner, Linux froze solid.  All I got was the caps-lock and scroll-lock 
keyboard LEDs blinking in unison.  I had to power down.

The hard drive is 20GB setup like this:
hda1=FAT32 Windows 2000 ~ 6GB
hda2=EXT3 /boot ~ 500MB
hda3=EXT3 / ~ 12GB
hda4=SWAP ~ the rest

I have setup the dual boot according to these instructions 
http://www.geocities.com/epark/linux/grub-w2k-HOWTO.html.  This puts GRUB on 
the first sector of the /boot partition and enters the LInux boot block as an 
entry for the Windows 2000 boot loader.  It has been working fine.  When it 
works right, this is what happens:

1-Windows 2000 boot loader asks for the OS.  I choose Linux.
2-The GRUB boot loader text flashes in the upper left corner of the screen for 
a moment and then the GRUB menu comes up.
3-I select the kernel I want to boot and up it comes.

After the disaster above, when I select Linux at step 1, I can see the word 
GRUB start to print in the upper left but then the computer reboots!

So far I have discovered:
- The drive is removable and inserting another 20GB drive with Windows 98 and 
Linux will boot either just fine so I don't think the system hardware is to 
blame.
- The Windows 2000 partition on the problem drive boots up and runs fine.
- Booting from the Red Hat 9.0 install CD in rescue mode allows me to get to 
the partitions.  "fsck -t ext3 -r /dev/hda2" and on hda3 complete very 
quickly and report no errors.
- The /dev/hda3/etc/grub.conf file looks fine.

I think I need to re-install GRUB back on the first sector of /boot 
(/dev/hda2) but I don't know how.  I have all of Knoppix at my disposal but I 
need some direction on how to proceed.  Any helps out there?

Alan