[PLUG] grub and fdisk problems mean what?

[eehouse]

I have a 3.5-year-old IBM desktop system with a 40G hard drive running
Debian testing.  I just downloaded the patches for kernel 2.6.18, built
it and installed the vmlinuz file in /boot and rebooted, expecting to see
the new kernel in grub's startup menu.  (This was my first reboot since
installing 2.6.17 a month or two back.)

Instead I got "Grub loading, please wait... Error 17"

So I toss in a handy Ubuntu live CD, and when it comes up take a look
at the hard drive.  There are supposed to be three partitions on this
dual-boot system.  IIRC hda2 is fat-32 (with Win2K on it), about 10
gig, and there are a couple of 15G ext2 partitions at hda1 and hda3.
But according to fdisk I have only one partition:

ubuntu at ubuntu:~$ sudo fdisk /dev/hda
[...]
Command (m for help): p

Disk /dev/hda: 40.0 GB, 40016019456 bytes
255 heads, 63 sectors/track, 4865 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/hda1               1           1        8001    1  FAT12

If I go ahead and mount /dev/hda1 (allowing mount to determine the
fs type itself) things look ok:

ubuntu at ubuntu:~$ mount | grep hda1
/dev/hda1 on /mnt type ext2 (rw)

And the size and amount of stuff on there look about right:

ubuntu at ubuntu:/mnt$ df /mnt/
Filesystem           1K-blocks      Used Available Use% Mounted on
/dev/hda1             14421344  13081608    607176  96% /mnt

But when I try to look at any of the files I get errors:

ubuntu at ubuntu:/mnt$ ls /mnt/boot
ls: /mnt/boot: Input/output error

I can't do anything to any of the files in /mnt without getting that 
same error.  

In addition, I can't mount any of the other partitions:

ubuntu at ubuntu:~$ sudo mount /dev/hda2 /mnt/
mount: special device /dev/hda2 does not exist

I don't know much about udev, which this cd is using, but I gather
that the device files being missing (and they are) could just mean
that udev didn't notice the partitions (rather than that they really
don't exist.)

Oh, and looking through the logs I found a suggestion that I run
e2fsck:

ubuntu at ubuntu:/var/log$ sudo e2fsck /dev/hda1
e2fsck 1.38 (30-Jun-2005)
The filesystem size (according to the superblock) is 3662812 blocks
The physical size of the device is 2000 blocks
Either the superblock or the partition table is likely to be corrupt!
Abort<y>?

Can anybody suggest what might be going on here, and maybe how to go
about fixing it?  Is this a situation I could have gotten into by
installing a new kernel?  Or did my superblock get trashed sometime
over the 40 days since I last re-booted?

Thanks,

--Eric
-- 
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* From the desktop of: Eric House, xwords at eehouse.org                        *
*        Crosswords 4.1.4 for PalmOS now ARM-native: xwords.sourceforge.net  *
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