Hello Felvol,
Can you attach your CrashReportClient logs found here:
C:\Program Files\Unreal Engine\4.0\Engine\Programs\CrashReportClient\Saved\Logs
And attach your launcher logs as well, found here (Replace User.Name with your windows user name):
C:\Users\User.Name\AppData\Local\UnrealEngineLauncher\Saved\Logs
Thanks!