grub-probe: error: cannot find a device for /boot (is /dev mounted?).

[ADRI HDEZ]

Just when I was trying to get Ubuntu 12.04LTS, for the first time in the
whole hard disk of my Acer Extensa 5620G, it doesn't install any boot manager
because it needs a special partition on my drive and it cannot find one to do this.

Thank you very much!

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: ubiquity 2.10.20
ProcVersionSignature: Ubuntu 3.2.0-29.46-generic-pae 3.2.24
Uname: Linux 3.2.0-29-generic-pae i686
ApportVersion: 2.0.1-0ubuntu12
Architecture: i386
CasperVersion: 1.315
Date: Fri Sep 28 09:58:48 2012
InstallCmdLine: noprompt cdrom-detect/try-usb=true persistent file=/cdrom/preseed/ubuntu.seed boot=casper initrd=/casper/initrd.lz quiet splash -- maybe-ubiquity
LiveMediaBuild: Ubuntu 12.04.1 LTS "Precise Pangolin" - Release i386 (20120817.3)
ProcEnviron:
 TERM=unknown
 PATH=(custom, no user)
 LANG=es_ES.UTF-8
 SHELL=/bin/bash
SourcePackage: grub-installer
UpgradeStatus: No upgrade log present (probably fresh install)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.