I just installed Vista RC1 on a machine to demo for my club.  After installing the larger apps, I installed ubuntu 6.10 meaning to dual boot the machine.  Vista originally occupied the entire disk.  Ubuntu offered to resize that partition and add the usual ones for it.  Everything seemed to go well.  However, on rebooting there was no dual boot menu.  GRUB was set to use a hidden menu with 3 seconds to ESCAPE before booting into ubuntu.  Looking at /boot/grub/menu.lst revealed no entry for any other OS after the magic part of the list.  sudo fdisk -l /dev/hda revealed the expected partitioning including the NTFS partition as /dev/hda1 although it was not marked as bootable (I do not know if it was after the initial install).

I switched over to a similar box which dual boots XP Pro and unbuntu 6.10 which works properly.  fdisk revealed essentially the same partitioning except that the Windows NTFS partition was marked bootable and the linux partition was NOT.  Huh?  I do notice /boot/grub/menu.lst under the Windows section includes a line with the "word" makeactive.

Anyway, I tried appending the other OS part of the grub menu from the box that works to the menu.lst on the box that won't boot windows vista and just changed the title.  But that does not work.  Next I tried booting from the Vista CD and running its repair function but that does not work either.  There was some text in one place that led me to think Vista may be somehow hiding a boot partition that I may have wiped out or made innaccessible.

Does anyone have any knowledge on this?

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Oh yes, I just remembered I meant to go mark hda1 as bootable and retry (though Vista not being able to repair makes me think that is not it).  Anyway I have to leave for an hour or so.  I'll check back in later.

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Be who you are and say what you feel, because those who mind don't matter and those who matter don't mind.  - Dr. Seuss