Comment 145 for bug 477169

-- A RECAP --------------------------------------

HOWTO: a "workaround" (before a really fix to this bug is found)

(1) Boot ubuntu manually [FOR PEOPLE WHO ARE NOT ABLE TO BOOT UBUNTU MANUALLY (see bellow)*]
(2) Check if /host is your windows directory (use Nautilus (the file manager!) and see):
    (2.1) YES: enter (at terminal) sudo cp /boot/grub/grub.cfg /host
    (2.2) NO: open Nautilus and find in what disk windows is. Then copy /boot/grub/grub.cfg to the root of that disk.
(3) Edit the grub.cfg (in the new location) with a text editor and delete the menuentry for kernel -16 and -15, (this was tested with kernel -14 only)
(4) Boot ubuntu until you get the grub prompt (press c if you see the menu)
(5) Enter the command ls -l (you must see the disks and partitions, usually something like (loop0), (hd0,1), (hd0,2), ...)
(6) Find where grub.cfg is, with the command cat (hdX,Y)/grub.cfg for X=0,1,... and Y=1,2,... (usually is in (hd0,1))
(7) Enter configfile (hd0,1)/grub.cfg (replace (hd0,1) with what you fund in (6)!)

You must see the grub menu and choose as usual...

Each time you boot, you must enter (7) (not too bad!)

Only one more thing (just for sure), make a copy of initrd.img-2.6.31-14-generic and keep it together with the copy of grub.cfg, because if you, or the system, updates the initrd's (update-initramfs) then the system will not boot, not even with the -14 kernel!!!

NOTE:
(A) If you don't have kernel -14 and the system worked fine before with kernel -15, please use that instead of kernel -14.
(B) As you can see, the problem is not one of corruption or bad configuration of file grub.cfg, it is much worse, grub(?) completely scrambles the content of many files inside root.disk!!! You can use the command cat in grub to verify that.
(C) This is completely orthogonal to the boot process, if in the near future a solution is fund this doesn't interfere with the normal boot process.

* HOWTO BOOT UBUNTU MANUALLY [works for most of the situations here]
At the grub prompt enter (if you don't get the grub prompt press c when you see the boot menu):

grub>linux /boot/vmlinuz-2.6.31-14-generic root=/dev/sda1 loop=/ubuntu/disks/root.disk ro quiet splash
grub>initrd /boot/initrd.img-2.6.31-14-generic
grub>boot

(if it doesn't work, change sda1 to sda2 or sda3 or ...)

** THIS DIDN'T WORK FOR ME! ALL I WANT ARE MY FILES...

Boot from the Live CD and at a terminal prompt, enter:
(1) sudo mkdir /win
(2) sudo mount /dev/sda1 /win (in your case should be sda2)
(3) sudo mkdir /vdisk
(4) sudo mount -o loop /win/ubuntu/disks/root.disk /vdisk

Et Voilá! You have the root.disk in /vdisk and the windows disk in /win. Now you can copy your precious files to windows, and reinstall Wubi!

*** I WANT TO TRY ANOTHER SOLUTION
Read entries #69 and #70 of this forum.