Dual boot problem - Vista disappeared from Grub menu

[Goh Lip]

On Sunday 19,September,2010 11:14 PM, Colin Law wrote:
> Hi
>
> On a machine with dual boot Ubuntu 10.04 and Vista which has been
> working fine for many months, suddenly Vista no longer appears in the
> boot menu (GRUB2).  I have not used Vista for a week so am not sure
> exactly when it happened.  I am not aware of any problems in the
> meantime apart from an update (don't know what to) which complained of
> a download not being available, but this seemed ok when the update was
> run again later.
>
> I have checked /etc/default/grub and run
> sudo update-grub
> which does not report the Vista partition.
> I am able to access the files on the vista partition from Ubuntu and
> it looks ok in gparted (showing the boot flag).
>
> Google reports lots of issues with grub disappearing after updating
> windows but I could not find any reports of Vista disappearing.
>
> Any suggestions will be much appreciated.
>
> Colin
>
Colin, try the following
sudo grub-mkdevicemap
sudo update-grub

You should check if you can boot up windows if you do the following at 
the grub prompt (press 'c' at grub menu)
set root=(hd0,x)
chainloader +1
boot

where (hd0,x) is /dev/sdax of the windows partition, (usually x=1)

Regards - Goh Lip