Graham, please follow the instructions in http://www.chiark.greenend.org.uk/ucgi/~cjwatson/blosxom/debian/2010-08-28-windows-applications-making-grub2-unbootable.html to gather more data, except rather than following up to this bug please file a *new* bug report against grub2 in Ubuntu.
Graham, please follow the instructions in http:// www.chiark. greenend. org.uk/ ucgi/~cjwatson/ blosxom/ debian/ 2010-08- 28-windows- applications- making- grub2-unbootabl e.html to gather more data, except rather than following up to this bug please file a *new* bug report against grub2 in Ubuntu.