System date wrong after boot

[Daniel]

$ lsb_release -rd
Description: Ubuntu Xenial Xerus (development branch)
Release: 16.04

After boot the system shows me Feb 11 17:29 for about 2 minutes - after then the time is corrected without any interaction by me. If I do a
$ sudo service ntp restart
the time is corrected almost changed immediately.

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: pcmanfm 1.2.4-1
ProcVersionSignature: Ubuntu 4.4.0-15.31-generic 4.4.6
Uname: Linux 4.4.0-15-generic i686
NonfreeKernelModules: nvidia_uvm nvidia
ApportVersion: 2.20-0ubuntu3
Architecture: i386
Config_pcmanfm_System_Lubuntu: Error: [Errno 2] Datei oder Verzeichnis nicht gefunden: '/etc/xdg/pcmanfm/Lubuntu/lubuntu.conf'
CurrentDesktop: LXDE
Date: Thu Mar 24 23:25:44 2016
ExecutablePath: /usr/bin/pcmanfm
InstallationDate: Installed on 2016-02-19 (34 days ago)
InstallationMedia: Lubuntu 16.04 LTS "Xenial Xerus" - Alpha i386 (20160217)
ProcEnviron:
 LANGUAGE=de_DE
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=de_DE.UTF-8
 SHELL=/bin/bash
SourcePackage: pcmanfm
Udisks_dump: Error: [Errno 2] Datei oder Verzeichnis nicht gefunden: 'udisks'
UpgradeStatus: No upgrade log present (probably fresh install)

[LStranger (andrej-rep)]

This is not related to pcmanfm in any way.