Multiple security audit events, Is my sytem compromised?

Heres a few sample of what im seeing in event viewer

An account was successfully logged on.
Subject:
Security ID: NULL SID
Account Name: -
Account Domain: -
Logon ID: 0x0
Logon Type: 0
Impersonation Level: -
New Logon:
Security ID: SYSTEM
Account Name: SYSTEM
Account Domain: NT AUTHORITY
Logon ID: 0x3E7
Logon GUID: {00000000-0000-0000-0000-000000000000}
Process Information:
Process ID: 0x4
Process Name:
Network Information:
Workstation Name: -
Source Network Address: -
Source Port: -
Detailed Authentication Information:
Logon Process: -
Authentication Package: -
Transited Services: -
Package Name (NTLM only): -
Key Length: 0
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Special privileges assigned to new logon.



Subject:


Security ID: NETWORK SERVICE


Account Name: NETWORK SERVICE


Account Domain: NT AUTHORITY


Logon ID: 0x3E4



Privileges: SeAssignPrimaryTokenPrivilege


SeAuditPrivilege


SeImpersonatePrivilege

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Code Integrity determined that the page hashes of an image file are not valid. The file could be improperly signed without page hashes or corrupt due to unauthorized modification. The invalid hashes could indicate a potential disk device error.



File Name: \Device\HarddiskVolume2\Windows\System32\guard64.dll
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And the one that troubles me the most is this one:



An attempt was made to query the existence of a blank password for an account.
Subject:
Security ID: LOCAL SERVICE
Account Name: LOCAL SERVICE
Account Domain: NT AUTHORITY
Logon ID: 0x3E5
Additional Information:
Caller Workstation: xxxx
Target Account Name: xxxxxxxx
Target Account Domain: xxxxx

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This last event I found a post about it here when googling it, could be system compromised or nasty rootkit malware. WTF is going on?
Im getting tired of this and about to cleanly install a Linux distro to have peace of mind. Someone please help me before I do so.

I would download and run MalwareBytes, using a rootkit scan and a reboot, running in "safe mode with networking" enabled.

Did that help?

Sorry for taking so long to respond, but Im afraid malware bytes or any typical AV would not have been able to resolve this issue.

Upon the time of this happening I talked to a computer security forensics expert and from what I explained to him, looks like my entire network was compromised. They had got in through wifi. Had to RMA all computer parts and start from scratch, since I believe I was infected by a hardware based BIOS rootkit which are not detectable by AVs.