パソコン：ASUS
最初のインストールは問題なくできました。
しかし、chromebook使用時に問題が生じて、出荷時に戻す作業を行いました。
その後、再度、ubuntuの再インストールを行った結果、以下のメッセージが表示されて、インストールができません
どのようにすればよろしいのでしょうか
ご教授願います。

sudo sh ~/Downloads/crouton -r trusty -t unity-desktop


We trust you have received the usual lecture from the local System
Administrator. It usually boils down to these three things:

    #1) Respect the privacy of others.
    #2) Think before you type.
    #3) With great power comes great responsibility.

WARNING: Signed boot verification is disabled; enabling it for security.
You can disable it again using:
sudo crossystem dev_boot_signed_only=0
Installing trusty-amd64 chroot to /usr/local/chroots/trusty
Downloading latest debootstrap...
2016-03-28 11:37:18 URL:https://anonscm.debian.org/gitweb/?p=d-i/debootstrap.git;a=snapshot;h=HEAD;sf=tgz [64377] -> "-" [1]
Patching debootstrap...
Downloading bootstrap files...
W: Cannot check Release signature; keyring file not available /usr/share/keyrings/ubuntu-archive-keyring.gpg
I: Retrieving Release

I: Unpacking lsb-base...
W: Failure while unpacking required packages.  This will be attempted up to five times.
W: See //debootstrap/debootstrap.log for details
W: Failure while unpacking required packages.  This will be attempted up to five times.
W: See //debootstrap/debootstrap.log for details
W: Failure while unpacking required packages.  This will be attempted up to five times.
W: See //debootstrap/debootstrap.log for details
W: Failure while unpacking required packages.  This will be attempted up to five times.
W: See //debootstrap/debootstrap.log for details
W: Failure while unpacking required packages.  This will be attempted up to five times.
W: See //debootstrap/debootstrap.log for details
I: Configuring required packages...
Failed to complete chroot setup.
Unmounting /mnt/stateful_partition/crouton/chroots/trusty...