LinuxQuestions.org - Problem: corrupt initrd, Ubuntu Intrepid won't boot.....

Hi all !

Sorry to step in with my crappy self-inflicted problem, but I really need some help on this one....

My laptop was recently rendered unworkable by a boot problem. I think I understand the problem by don't know where to start to fix it, so any help is *greatly* appreciated. Here we go:

I recently installed Kubuntu 8.10 Intrepid on my laptop using a net install. The problem is that the CD/DVD drive is dead (hardly ever used it anyway) and the BIOS ignores bootable USB drives. The only one I have that it would detect at all (but refuses to boot on) was an old 256MB one, on which I put the minimal debian/ubuntu network installer using unetbootin.

On the install I had before (Kubuntu 7.04 Feisty) I added an option in grub to boot on this stick and installed Intrepid that way. (I didn't want to go through all the incremental upgrades, and the 7.04->7.10 upgrade path was broken last week anyway...). As grub would crash when installing it, I asked the installer to put LILO instead. My hard drive is partitioned as

sda1 : /boot
sda2 : /
(then swap, home...)

SO -- just for you to get an idea of the mess I'm handling...

After the install, i had problems with the drivers for my wireless (RaLink RT2500), so I decided to "manually" compile another version of the driver (RT2500 legacy from CVS). I *think* this is the source of my
problem. After restarting the box, the boot sequence would end up with the following messages (copy-typed by hand...)

[ 2.048095] RAMDISK: Compressed image found at block 0
[ 2.394008] invalid compressed format (err=2)
[ 2.447976] VFS: Cannot open root device "sda2" or unknown-block(0,0)
[ 2.448054] Please append a correct "root=" boot option; here are the available partitions:
[ 2.448131] Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)

It seems that the init ramdisk image got corrupt, which prevents the kernel from having the module(s) necessary for accessing the hard drive and mounting the boot partition. The problem is, I have no other way to boot the box. The only way to solve this that I could think of are:

1- Make lilo boot another kernel. I have two kernels installed in my /boot, the other one might be working, but it's not in lilo.conf. Is there a way to boot it from the LILO boot prompt ?
2- Make lilo boot the aforementioned flash drive, same question...
3- Put the hard drive in an external enclosure and use another box to fix the initrd, but I don't really know how to do it.

Any ideas/comments/advice ?

Thanks in advance !

T.