Member Avatar for 05026652

Hey there,

Well certainly a rookie mistake made on my part here. I have a dual boot machine with Ubuntu and Win 7 installed. Yesterday I had a little play with my ubuntu install and upgraded to 10.04 Lucid Lynx. All was well until I went to boot into windows. When I select this option, the screen goes black, as ready to load then a little cursor is found in the top right hand corner flashing constantly. It looks similiar boot style to the Ubuntu OS.

Any idea what has gone on?

I can access my two HD drives in Ubuntu so data loss isnt a problem.

Any ideas would be great.

Thanks

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  • Latest Post Latest Post by join2helpisfail

Dani AI

Generated

The symptom (black screen then a small flashing cursor) most often indicates the Windows boot code is not being chainloaded correctly rather than file-level data loss — mounting the NTFS partitions from Ubuntu is a good sign. The shortest, safest triage is: identify the real Windows boot partition, let GRUB detect it, and only if Windows' boot files are damaged use the Windows Recovery console to repair the BCD and then restore GRUB.

Start by identifying partitions and the boot flag from Ubuntu:

sudo fdisk -l
sudo blkid
sudo parted -l

Look for NTFS partitions and a small "System Reserved" partition (about 100 MB) that should have the boot flag. To set the boot flag (replace /dev/sda and partition number as appropriate):

sudo parted /dev/sda set 1 boot on

Make GRUB rescan for other OSes:

sudo os-prober
sudo update-grub

To test chainloading immediately at boot (as suggested), edit the Windows entry in the GRUB menu or press 'c' for a GRUB prompt and use:

ls
set root=(hd0,1)   # choose the partition that ls shows contains the Windows boot files
chainloader +1
boot

If Windows' boot sector is corrupted, repair it from a Windows 7 Install/Recovery DVD (System Recovery Options -> Command Prompt):

bootrec /fixmbr
bootrec /fixboot
bootrec /rebuildbcd

That will overwrite GRUB; restore GRUB from an Ubuntu live session by chrooting into the installed root and reinstalling GRUB:

sudo mount /dev/sdaX /mnt
for i in /dev /dev/pts /proc /sys; do sudo mount --bind $i /mnt$i; done
sudo chroot /mnt
grub-install /dev/sda
update-grub
exit

Back up the MBR beforehand (optional):

sudo dd if=/dev/sda of=~/mbr-backup.bin bs=512 count=1

Notes: 's EasyBCD is useful when preferring the Windows bootloader as primary (run from Windows), and automated tools like Boot-Repair or Super Grub Disk can simplify recovery. Many reports in this thread (see and ) were bootloader/partition issues rather than an Ubuntu bug.

Recommended Answers

All 6 Replies

Member Avatar for khakilang

I believe there is a bug in the Lucid Lynx. I don't know whether there is a fix. Make a bug report on the launch pad and update Lucid Lynx and see how it turns out.

Member Avatar for mooreted

I believe there is a bug in the Lucid Lynx. I don't know whether there is a fix. Make a bug report on the launch pad and update Lucid Lynx and see how it turns out.

There's always EasyBCD.

Member Avatar for thuekx

are you install with fresh cd or upgrade with internet connection?
actually i'm install dual boot with windows 7 is not something wrong its good so far...
may be you can install lucid with fresh cd its recommended

Member Avatar for Ken S

I upgraded to Lucid over the internet and when Grub loaded I could no longer boot windows 7. It would just go back to grub os choice. I re installed windows and now i dont have a option to load ubuntu. I tried to re install Grub but it won't work.

Member Avatar for Bloody1004

installed 10.04 yesterday by upgrading 9.10 from internet which managed to corrupt the mbr and now I can not load windows 7 anymore. Also setup updated bios drivers that caused the network card to not work!!

Is there anyone who managed to fix dual boot problem with windows 7 and Ubuntu 10.04?

Member Avatar for join2helpisfail

Yeah dude... when you upgraded your Ubuntu, it reinstalled the Grub (Windows equivalent of the Boot loader). You probably have your Windows on a weird partition so the default Grub partition doesn't find Windows anymore. Given the number of ways you can setup your loader though, there could be other explanations, but I'm sure it's your loader. When you start your computer at the OS selection screen, is it Grub? or Boot loader? If it's Grub, there should be an option to "edit" your boot config... in there, just simply modify the partition (e.g. "hd0,1" where the first number represents the physical drive and the second the partition number on that media. Only fiddle with the numbers, not the hd in front because it may be different depending on what type of hard drive you have :D ), don't worry the changes here aren't permanent so it's safe to experiment. Once you figure out the correct partition where your Windows Boot loader is located, you can make these changes permanent within your Ubuntu terminal. Good luck, and cheers!

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