Quote:Just a footnote (don't know if Hybrid is aware of this) - grub.cfg under GRUB2 isn't intended to be manually edited[1][2], unlike older GRUB-legacy. There are a number of script files in /etc/grub.d which are parsed when running "grub-update" and they rebuild the grub.cfg file - the "30_os-prober" script is supposed to scan and detect other non-Linux OSes and add them into the GRUB menu file for you (other Linux distros are detected first with "10_linux").
I was aware of this, at one point I was thinking of suggesting editing the config file manually one time just to get it to boot once, then fix the underlying issue and have it regenerate the file with update-grub. Then I realised editing the boot lines at runtime was a much better idea!
It is definitely worth reiterating though -- you can edit the GRUB2 config file, but your OS then might overwrite your changes at a later date. It's always a much better idea to only edit the files that are used to generate those scripts, as you rightly point out, Dave, and subsequently have update-grub do the rest for the grub.cfg file.
The good thing is we solved this in the end, even if it was fiddly. I know I've said this a lot now, but why did it fail in the first place!? :P
Anyway, as I said, all fixed now, so the GRUB config file is in sync with the partitions, so everything should work great now, even as software updates get installed.