upgrade 14.4 to 16.4 no start possible

[Bruno Todde]

When I upgrade the pc from 14.4 to 16.4 the pc won't start.
I am using 2 systems, Ubuntu and Windows 10.
When I start the pc after upgrading, I have to choose Ubuntu or Windows and then I cannot go further, it freezes

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: ubuntu-release-upgrader-core 1:0.220.9
ProcVersionSignature: Ubuntu 4.2.0-42.49~14.04.1-generic 4.2.8-ckt12
Uname: Linux 4.2.0-42-generic x86_64
ApportVersion: 2.14.1-0ubuntu3.23
Architecture: amd64
CrashDB: ubuntu
Date: Wed Mar 29 17:02:25 2017
InstallationDate: Installed on 2017-03-23 (5 days ago)
InstallationMedia: Ubuntu 14.04.4 LTS "Trusty Tahr" - Release amd64 (20160217.1)
PackageArchitecture: all
ProcEnviron:
 LANGUAGE=nl
 PATH=(custom, no user)
 LANG=nl_NL.UTF-8
 SHELL=/bin/bash
SourcePackage: ubuntu-release-upgrader
UpgradeStatus: Upgraded to trusty on 2017-03-29 (0 days ago)
VarLogDistupgradeAptlog:
 Log time: 2017-03-29 16:44:56.753842
 Log time: 2017-03-29 16:45:15.103912
 Log time: 2017-03-29 16:46:04.578987
 Log time: 2017-03-29 17:02:34.971326
VarLogDistupgradeTermlog: