Update hangs configuring grub; system does not hang

[cedial]

Ubuntu was running in a VirtualBox virtual machine ver 4.3.12; Windows 7 host machine. Same thing happens with a Windows 8.1 host.

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: update-manager 1:0.196.12
ProcVersionSignature: Ubuntu 3.13.0-32.57-generic 3.13.11.4
Uname: Linux 3.13.0-32-generic x86_64
ApportVersion: 2.14.1-0ubuntu3.2
Architecture: amd64
CurrentDesktop: Unity
CurrentDmesg.txt:
 [ 12.701364] vboxsf: Successfully loaded version 4.3.12 (interface 0x00010004)
 [ 41.017413] audit_printk_skb: 150 callbacks suppressed
 [ 41.017424] type=1400 audit(1406897871.009:62): apparmor="STATUS" operation="profile_replace" profile="unconfined" name="/usr/lib/cups/backend/cups-pdf" pid=2262 comm="apparmor_parser"
 [ 41.017431] type=1400 audit(1406897871.009:63): apparmor="STATUS" operation="profile_replace" profile="unconfined" name="/usr/sbin/cupsd" pid=2262 comm="apparmor_parser"
 [ 41.017752] type=1400 audit(1406897871.009:64): apparmor="STATUS" operation="profile_replace" profile="unconfined" name="/usr/sbin/cupsd" pid=2262 comm="apparmor_parser"
Date: Fri Aug 1 09:01:30 2014
ExecutablePath: /usr/bin/update-manager
GsettingsChanges:
 b'com.ubuntu.update-manager' b'show-details' b'true'
 b'com.ubuntu.update-manager' b'window-height' b'394'
 b'com.ubuntu.update-manager' b'first-run' b'false'
 b'com.ubuntu.update-manager' b'window-width' b'484'
 b'com.ubuntu.update-manager' b'launch-time' b'1406897858'
InstallationDate: Installed on 2014-04-18 (105 days ago)
InstallationMedia: Ubuntu 14.04 LTS "Trusty Tahr" - Release amd64 (20140417)
InterpreterPath: /usr/bin/python3.4
PackageArchitecture: all
ProcEnviron:
 LANGUAGE=en_US
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: update-manager
UpgradeStatus: No upgrade log present (probably fresh install)