[sclug] Grub2 Reinstall issue

[Matt Cox]

Hi,

I run a windows/Linux dual boot system.  I was running Vista/Ubuntu
9.10, but have just installed Windows 7 in place of Vista leaving
Ubuntu untouched.

I've reinstalled legacy Grub many times on various machnies, but this
is the first time I've tried to do it with Grub2.  I managed to find
instructions to reinstall it via the LiveCD, but I am having issues.
These are the commands I have using:

<snip>
ubuntu at ubuntu:~$ sudo fdisk -l

Disk /dev/sda: 320.1 GB, 320072933376 bytes
143 heads, 26 sectors/track, 168139 cylinders
Units = cylinders of 3718 * 512 = 1903616 bytes
Disk identifier: 0x3d56278a

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1       84609   157288118    7  HPFS/NTFS
/dev/sda2           84610      167018   153198331   83  Linux
/dev/sda3          167019      168139     2083939   82  Linux swap / Solaris

Disk /dev/sdb: 320.1 GB, 320072933376 bytes
38 heads, 6 sectors/track, 2741852 cylinders
Units = cylinders of 228 * 512 = 116736 bytes
Disk identifier: 0xe76becd9

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1   *           1     2741852   312571125    7  HPFS/NTFS
ubuntu at ubuntu:~$ sudo mount /dev/sda2 /mnt
ubuntu at ubuntu:~$ sudo grub-install --root-directory=/mnt /dev/sda
grub-setup: warn: Your embedding area is unusually small.  core.img
won't fit in it.
grub-setup: warn: Embedding is not possible.  GRUB can only be
installed in this setup by using blocklists.  However, blocklists are
UNRELIABLE and its use is discouraged.
grub-setup: error: Cannot read `/grub/core.img' correctly
ubuntu at ubuntu:~$
</snip>

 I'm perplexed as 9.10 and Vista have played happily until now and
I've made no changes to any of the partitions.  All I have done is
install Windows 7 on the existing Vista one.  The ins/outs of these
messages are a bit above my knowledge so any assistance would be
greatly appreciated.   I've found the error message in google
searches, but not a clear cut answer.  If I have to start messing
about with partitions is there any way I can do this in a
non-destructive manner?

Its a bit of a pain since I can't boot into Linux at the moment.

Cheers,

Matt.