Win8.1 starts on its own

Problem is simple. Sometimes when my computer is on sleep mode or hibernating, it will start up and show login screen. When I press shutdown button it tells me that other users are logged in and they may lose any unsaved files.

This has happened a few times, last night again machine booted up.

Have scanned the machine with Avast Antivirus, Malwarebytes antimalware and Malwarebytes Anti-Rootkit BETA, they all said system clean.

Windows task scheduler has no task that would require boot up.

Windows logs show that at that time currently logged in user account was named SYSTEM, is this normal?

What could cause this kind of behavior? Infection?

What should I do to that error message concerning iseguard64.dll?

Attached text file MAKEPELIKONE has my system specs and file Logons is part on windows security logs.

Truly hope this is not a virus or anything.

Sorry if there are any typos, english is my second language.

Hi Marko V, and welcome to our forums,
 
There can be a number of reasons for this sort of behaviour,  from sleep/hibernate, but one thing is sure and that is with a desktop computer if you switch off the line( power) to the computer at the wall socket after setting a full shutdown, your computer will not restart on its own!
 
However if you want to try and track down the service or app that is initiating the restart then the following is a good place to start.

http://windowssecrets.com/forums/showthread.php/159067-Computer-turns-itself-on

Regards

paws