warm restart automatically, log in screen not displayed

system starts with one or more error messages, then performs warm reset (sometimes message is visible), then shows black screen. log in possible after closing lid and waking up laptop again, system then runs without any issues.

14.04 lts

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: linux-image-4.4.0-36-generic 4.4.0-36.55~14.04.1
ProcVersionSignature: Ubuntu 4.4.0-36.55~14.04.1-generic 4.4.16
Uname: Linux 4.4.0-36-generic x86_64
NonfreeKernelModules: nvidia
ApportVersion: 2.14.1-0ubuntu3.21
Architecture: amd64
CurrentDesktop: Unity
Date: Fri Sep 16 08:21:10 2016
GvfsMonitorLog: Monitoring events. Press Ctrl+C to quit.
HotplugNewDevices:

HotplugNewMounts:

InstallationDate: Installed on 2015-11-08 (312 days ago)
InstallationMedia: Ubuntu 14.04.3 LTS "Trusty Tahr" - Beta amd64 (20150805)
ProcEnviron:
 LANGUAGE=de_DE
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=de_DE.UTF-8
 SHELL=/bin/bash
SourcePackage: linux-lts-xenial
Symptom: storage
UdevMonitorLog:
 monitor will print the received events for:
 UDEV - the event which udev sends out after rule processing
UdisksMonitorLog:
 Monitoring the udisks daemon. Press Ctrl+C to exit.
 08:21:25.348: The udisks-daemon is running (name-owner :1.77).
UpgradeStatus: No upgrade log present (probably fresh install)