impossible installation due to grub installer error

[filippo]

When I try to install ubuntu (distro 14.04) from a usb bootloader, at the end of the process,I got an error ''the installation of the package 'grub-efi-amd64-signed' is impossible.Without grub, the installed system won't load''.

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: ubiquity 2.18.8.9 [modified: lib/partman/automatically_partition/question]
ProcVersionSignature: Ubuntu 3.19.0-25.26~14.04.1-generic 3.19.8-ckt2
Uname: Linux 3.19.0-25-generic x86_64
ApportVersion: 2.14.1-0ubuntu3.11
Architecture: amd64
CasperVersion: 1.340.2
Date: Sat Sep 26 11:48:12 2015
InstallCmdLine: BOOT_IMAGE=/casper/vmlinuz.efi file=/cdrom/preseed/ubuntu.seed boot=casper only-ubiquity quiet splash --
LiveMediaBuild: Ubuntu 14.04.3 LTS "Trusty Tahr" - Beta amd64 (20150805)
ProcEnviron:
 LANGUAGE=it_IT.UTF-8
 TERM=linux
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=it_IT.UTF-8
SourcePackage: grub-installer
UpgradeStatus: No upgrade log present (probably fresh install)

[Launchpad Janitor (janitor)]

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

[Richard Myer (rmcd32)]

have tried lots of reccomends including manually checking the partitions,
always get this failure. Only one drive on this netbook, completely devoted to this install.
Cannot get through install even with minimal system