Event Viewer showing unauthorized logons?

[Logonhistory]

Today I just got back to my apartment from an weekend out of town. When I logged into Windows 8, I noticed that some programs were running what really shouldn't be. I checked the Event Viewer and saw a series of logon events that happened while I was not home.
Before I left for the weekend, I didn't shutdown the laptop but I closed the lid so any one wishing to use it must enter a password to login to Windows, and I am the only person that knows the password. The strange logon events recorded on Event Viewer made me suspicious of my roommates. I don't want to start questioning them at this point. Could someone help me understand what was happening to my computer when I was away? Thank you very much.
Here's the security log for when I was away:

Audit Success 2016-02-21 2:50:17 PM Microsoft Windows security auditing. 4672 Special Logon
Audit Success 2016-02-21 2:50:17 PM Microsoft Windows security auditing. 4624 Logon
Audit Success 2016-02-21 2:50:17 PM Microsoft Windows security auditing. 4672 Special Logon
Audit Success 2016-02-21 2:50:17 PM Microsoft Windows security auditing. 4624 Logon
Audit Success 2016-02-21 2:49:15 PM Microsoft Windows security auditing. 4672 Special Logon
Audit Success 2016-02-21 2:49:15 PM Microsoft Windows security auditing. 4624 Logon
Audit Success 2016-02-21 2:48:56 PM Microsoft Windows security auditing. 4672 Special Logon
Audit Success 2016-02-21 2:48:56 PM Microsoft Windows security auditing. 4624 Logon
Audit Success 2016-02-21 9:42:25 AM Microsoft Windows security auditing. 4672 Special Logon
Audit Success 2016-02-21 9:42:25 AM Microsoft Windows security auditing. 4624 Logon
Audit Success 2016-02-21 9:41:17 AM Microsoft Windows security auditing. 4672 Special Logon
Audit Success 2016-02-21 9:41:17 AM Microsoft Windows security auditing. 4624 Logon
Audit Success 2016-02-21 2:51:55 AM Microsoft Windows security auditing. 4672 Special Logon
Audit Success 2016-02-21 2:51:55 AM Microsoft Windows security auditing. 4624 Logon
Audit Success 2016-02-21 2:51:39 AM Microsoft Windows security auditing. 4672 Special Logon
Audit Success 2016-02-21 2:51:39 AM Microsoft Windows security auditing. 4624 Logon
Audit Success 2016-02-21 2:50:20 AM Microsoft Windows security auditing. 4672 Special Logon
Audit Success 2016-02-21 2:50:20 AM Microsoft Windows security auditing. 4624 Logon
Audit Success 2016-02-21 2:50:19 AM Microsoft Windows security auditing. 4672 Special Logon
Audit Success 2016-02-21 2:50:19 AM Microsoft Windows security auditing. 4624 Logon
Audit Success 2016-02-20 8:14:10 PM Microsoft Windows security auditing. 4672 Special Logon
Audit Success 2016-02-20 8:14:10 PM Microsoft Windows security auditing. 4624 Logon
Audit Success 2016-02-20 2:50:09 PM Microsoft Windows security auditing. 4672 Special Logon
Audit Success 2016-02-20 2:50:09 PM Microsoft Windows security auditing. 4624 Logon
Audit Success 2016-02-20 2:50:09 PM Microsoft Windows security auditing. 4672 Special Logon
Audit Success 2016-02-20 2:50:09 PM Microsoft Windows security auditing. 4624 Logon
Audit Success 2016-02-20 2:48:50 PM Microsoft Windows security auditing. 4672 Special Logon
Audit Success 2016-02-20 2:48:50 PM Microsoft Windows security auditing. 4624 Logon
Audit Success 2016-02-20 2:48:19 PM Microsoft Windows security auditing. 4672 Special Logon
Audit Success 2016-02-20 2:48:19 PM Microsoft Windows security auditing. 4624 Logon
Audit Success 2016-02-20 1:42:48 PM Microsoft Windows security auditing. 4672 Special Logon
Audit Success 2016-02-20 1:42:48 PM Microsoft Windows security auditing. 4624 Logon
Audit Success 2016-02-20 1:42:14 PM Microsoft Windows security auditing. 4672 Special Logon
Audit Success 2016-02-20 1:42:14 PM Microsoft Windows security auditing. 4624 Logon
Audit Success 2016-02-20 2:50:50 AM Microsoft Windows security auditing. 4672 Special Logon
Audit Success 2016-02-20 2:50:50 AM Microsoft Windows security auditing. 4624 Logon
Audit Success 2016-02-20 2:50:26 AM Microsoft Windows security auditing. 4672 Special Logon
Audit Success 2016-02-20 2:50:26 AM Microsoft Windows security auditing. 4624 Logon
Audit Success 2016-02-20 2:50:09 AM Microsoft Windows security auditing. 4672 Special Logon
Audit Success 2016-02-20 2:50:09 AM Microsoft Windows security auditing. 4624 Logon
Audit Success 2016-02-20 2:50:08 AM Microsoft Windows security auditing. 4672 Special Logon
Audit Success 2016-02-20 2:50:08 AM Microsoft Windows security auditing. 4624 Logon

 

[CuriousOne]

Did you get an answer?

 

[Logonhistory]

No I haven't got an answer yet.

 

[derekimo]

This may shed some light on it for you,

Event viewer - special Logon - NT Authority - Windows 7

I have a bunch of those too,



I don't think you need to worry about them.