The above error about inability to read core.img got replaced with "error: non-sector-aligned data is found in the core file" somewhere between 1.99-19 and 1.99-20 (which got fixed 1.99-21 - #666992) so this I guess may be closed).
(For people hitting the same, I could work around it by reformatting /boot to ext3 on *some* of the affected systems. NFC. Running grub-setup with --debug showed that it really was unable to find the file, would suggest some cryptic bug in ext2.mod. Systems with grub installed to MBR were unaffected, however that is not really an option for everyone, e.g. cannot be used on dual-boot boxes using Bitlocker-encrypted Vista/W7 system partition.) -- To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org