Dual boot problem - Vista disappeared from Grub menu

[Goh Lip]

On Wednesday 22,September,2010 12:43 AM, Colin Law wrote:
>> Colin, try the following
>> >  sudo grub-mkdevicemap
>> >  sudo update-grub
> Thanks for the help.
> OK, did that, no change.
>
>> >
>> >  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)
> This boots into Vista ok.  So that means that Vista is ok, but for
> some reason grub does not see it.
> I see from the grub docs that I can manually include the relevant boot
> option, but it would be better if I could persuade grub to work it out
> for itself.   Any ideas where to go next?

Colin, boot into ubuntu  and
sudo grub-install /dev/sda

Hope this works, but I am reluctant to suggest the use of "-f" or 
"--recheck --root-directory". I agree with you that it is better to let 
grub work it out than a manual entry, but Colin, Windows parameters 
*never* change in the grub menu. (Say, compared to linux kernel changes)

Good luck - Goh Lip