Could not install boot-loader to /dev/sdb

Attempted to install Lubuntu 12.04 64bit, but got above error.

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: ubiquity 2.10.16
ProcVersionSignature: Ubuntu 3.2.0-23.36-generic 3.2.14
Uname: Linux 3.2.0-23-generic x86_64
ApportVersion: 2.0.1-0ubuntu5
Architecture: amd64
CasperVersion: 1.315
Date: Wed May 16 18:28:19 2012
InstallCmdLine: bootkbd=us console-setup/layoutcode=en_US console-setup/variantcode=nodeadkeys locale=us_us persistent noprompt cdrom-detect/try-usb=true file=/cdrom/preseed/lubuntu.seed boot=casper initrd=/casper/initrd.lz splash --
LiveMediaBuild: Lubuntu 12.04 "Precise Pangolin" - Release amd64 (20120423)
ProcEnviron:
 LANGUAGE=en_AU.UTF-8
 TERM=unknown
 PATH=(custom, no user)
 LANG=en_AU.UTF-8
 SHELL=/bin/bash
SourcePackage: grub-installer
UpgradeStatus: No upgrade log present (probably fresh install)