Wubi install of Ubuntu Karmic won't boot after Grub2 update

[nUboon2Age]

@Orrin Zirbel wrote on https://answers.launchpad.net/wubi/+question/122771

My Dell inspiron 1525 laptop runs Windows Vista Home Premium (Intel Core2 Duo, 4GB RAM, 32-bit operating system). Ubuntu was added in December of 2009 (Karmic) and, until today, has started off a dual-boot menu.
On August 25 2010, I went to Ubuntu and loaded a large number of system updates. The process seemed to go well until it stopped at a question about where to place Grub. I may not have given the correct answer (I told it to proceed) because now the Windows Boot Manager never gets me to Ubuntu. If I select "Ubuntu" in Windows Boot Manager, I get a brief set of messages and then the system takes me back to Windows Boot Manager. Fortunately, at this point I can select Windows and it operates normally.

The messages are:
Try (hd0,0): FAT16: No WUBILDER
Try (hd0,1): NTFS5: No wubildr
Try (hd0,2): NTFS5:
error unknown command 'loadfont'
error file not found

In my files I have the following:
c:\ubuntu\disks\boot\grub (folder is empty)
c:\ubuntu\disks\root.disk (modified 8/25/2010) 17,145,856Kb
c:\ubuntu\disks\swap.disk (modified 12/18/2009) 262,144Kb
c:\ubuntu\install\.fuse_hidden (modified 12/18/2009) 707,376Kb
c:\ubuntu\winboot\wubildr (modified 12/18/2009) 79Kb
c:\ubuntu\winboot\wubildr.cfg (modified 12/18/2009) 2Kb
c:\ubuntu\winboot\wubildr.mbr (modified 12/18/2009) 8Kb
c:\ubuntu.ico (modified 12/18/2009)
c:\uninstall-wubi.exe (modified 12/18/2009)

I am new to using Ubuntu, and would appreciate any help I could get to be able to boot normally as before.

I have removed Ubuntu from this machine and am running it as a Vista-only machine again.

EDIT: (2010/12/13, by Mayukh)
I have tested all ubuntu >= 9.10 as they ship with grub2. I found the issue to occur
1. after updates (9.10, 10.04, 10.10)
2. without updates (10.04, 10.10)
3. even before it is fully installed! (10.10)

[nUboon2Age (nuboon2age)]

@Orrin Zirbel: looking over the symptoms i think yours is a separate from bug #609815. That one actually stops the computer from booting at all, whereas yours is only preventing booting the Wubi install from booting. I hope you don't mind that i took the step to create a new bug #626503. Could you please take the time to go to this bug #626503 web page and enter a comment confirming my guess that you had Ubuntu 9.10 Karmic Koala (and had not upgraded it to Ubuntu 10.04 Lucid Lynx)? Also if there is any additional information you remember please add it here.

[Orrin Zirbel (ozirbel8327)]

@nUboon2Age : Thank you for looking at this. I believe you are correct, my first installation of Ubuntu was December 18, 2009. I had not upgraded it after that. Between April and August of 2010, I really did not use Ubuntu, so I would have missed the upgrade to another version.
I'm sorry I do not have more information to offer, except that I have since converted two older Dell machines to Ubuntu 10.04 and it is working great. No dual boot on these machines.

[Mayukh (mayukh-mukherjee)]

I have found the issue in other recent versions also, and sadly, in cases without updates.

INSTANCE #1: (Without any updates)

A few days back I mentioned @ https://bugs.launchpad.net/grub/+bug/477104/comments/185 (which is on same issue in karmic) that by copying wubildr and wubildr.mbr from X:\ubuntu\winboot\wubildr onto X:\ solved the issue. After this change I updated ubuntu (maverick), and could boot fine.

But I was wrong. A day later I couldn't boot again, and got the same old "Alert! /host/.../root.disk not found. Dropping to shell!" followed by (initrafms) prompt. Here I tried a few recovery steps mentioned in Wubi megathread (http://ubuntuforums.org/showthread.php?t=1639198). After trying to manually boot, I got an "ata10: SATA link down" error. I thought something was wrong with my partition, so I rebooted to windows, and uninstalled wubi. I deleted the partition and formatted afresh. I have two drives - sda (windows), sdb (ubuntu). The exact partitions are verified by boot-info-script. I did a 20GB clean maverick wubi install on the 22GB sdb1. I logged in to ubuntu desktop, and unlike other occasions, did not run update. I shut down ubuntu. I booted again, and found myself at initrafms prompt!

In the initrafms prompt, the contents of /host were found to be same as that of sda1, i.e. C:. To make the bootloader find root.disk in it, it must point to /dev/sdb1, because there is no root.disk in C:. Now I mounted /dev/sdb1 to /mnt/win1. When I checked its contents, it was same as /dev/sda1, and NOT sdb1. I suspect this issue is because of a different partition of wubi than C:. If wubi was installed in C:, /host would have always had root.disk.

When I checked /dev, I could see all partitions of sda and sdb. The fact is the drives are not mounted properly.

INSTANCE OF ISSUE #2 (During install)

Although it uses the same bootloader+wubi combo as the affected ones, I gave Kubuntu Maverick a try. The issue could be reproducible even quicker. This time I got "Alert! /host/.../root.disk not found. Dropping to shell!" just after the machine rebooted for the second time during installation (to recall the two instances of reboot during installation - 1st is when you complete wubi wizard in windows, 2nd is when it finishes installation before loading the desktop).

Not simply chkdsk, I did full format of the partition before install, if you are asking (I don't think it matters).

In the last one week, I have tested all ubuntu >= 9.10 as they ship with grub2. I found the issue to occur
1. after updates (9.10, 10.04, 10.10)
2. without updates (10.04, 10.10)
3. even before it is fully installed! (10.10)

Practically, almost at EVERY instance of grub2+wubi usage. The lone savior in grub2 usage is base 9.10 without updates. But I can confirm consistency in 10.04 and 10.10, and also in 9.10 by updating to a later kernel than 2.6.31-14 and a later grub2 than 1.97~beta4-1ubuntu3 (the base versions that come with 9.10). I think the issue is therefore with the later versions of them combined with wubi. Since I don't get the issue in base wubi 9.10 without updates, it would be incorrect to suspect my bios or drives. And of course there is no issue with ...