Kernel Panic on boot

Hi all,

Last week I installed Ubuntu 8.10 onto my wife's desktop, setup to dual boot with Windows XP Home. (She's been using Ubuntu on my laptop since 8.04 was released and now despises Windows)

It installed happily and ran fine with no problems. Until yesterday. She phoned me up at work and said it is starting to run really slowly. She tried rebooting and it was bombing out showing her a screen of text. Grub still allowed you to select WinXP, which booted happily (in XP's usual slow and befuddled way).

When I got home I found that the problem was caused by Ubuntu having a Kernel Panic.

I haven't got the full text of the error with me (as I'm at work), but I can post it later. The basic message was:
Cannot open root device "<NULL>" or unknown-block(8,1)
Please append a correct "root=" boot option
Kernel panic - not syncing: VFSUnblele to mount roofsfs oun-knownwn block(8,1)

So I thought I had a simple fix, boot to the G-Parted Live CD, format the ext3 partition, boot using the Live CD and install Ubuntu afresh.

Except G-Parted and the Live CD kept giving the same problem..intermittently. I eventually got it booted into G-Parted and formatted the whole disk (removing WinXP) setting up an ext3 partition and a Linux Swap partition. Booting onto the live CD caused it to bomb again. So I tried G-Parted again (in failsafe mode), it also bombed, reboot, and G-Parted (failsafe) again and that worked, then reformatted the ext3 partition (yet again). Booted to the live CD, got to start installing, got half way through and Kernel Panic again.
This went on for most of the evening until I gave up.

I'm leaning towards the problem being an imminent HDD failure, but wanted to confirm what others thought before I go buy another HDD (given that Ubuntu was working very well on the machine the day before, and that both G-Parted Live and Ubuntu LiveCD's now give the same error).

Thanks
-Roger