Comment 11 for bug 524434

Same problem here with an virtualized Ubuntu 10.04 under XenServer 5.6: The grub installer does not find the virtual hard disks /dev/xvdX.

Trying to install grub results in:

Setting up grub-pc (1.98-1ubuntu6) ...
dpkg: error processing grub-pc (--configure):
subprocess installed post-installation script returned error exit status 1
Errors were encountered while processing:
grub-pc
E: Sub-process /usr/bin/dpkg returned an error code (1)

After using nutznboltz's patch file everything works fine.