Windows 7 build 7601 copy may not be genuine and more problems

Tl;dr: Windows 7 says my copy is not genuine (bought the pc with the OS second hand so I cannot know if it is a legitimate problem or not).

I cannot access normal Windows, only safe mode. Anti-spyware and anti-virus find nothing that may be causing this and it all started after 10 months of normal usage. What can I do?

A pop up in the system tray appeared today, informing me that my copy of Windows may not be genuine, and then a pop-up (in the style of system errors) that said that I may have been victim to software counterfeit. When I minimized my browser, I saw that my wallpaper had been replaced by a black one with the words "Windows 7 build 7601 may not be genuine" in the bottom right corner.

I restarted my computer after that and after logging in my account there was only the black screen with the message in the bottom right corner and a cursor that could be moved. No icons, no taskbar, no task manager or right click menus. Nothing. So I entered into safe mode and tried to find a solution, to no avail.

I uninstalled my Advanced System Optimizer (cracked) cause I read that it may be causing trouble and scanned with Malware Antibytes, Avast, ccleaner and Spybot S&D. Spybot, ccleaner and Malware found some minor things but nothing that affected my problem (there was malware in System Optimizer, at least according to Spybot). Scf /scannow cannot find something wrong with the system files and I cannot run slmgr commands in safe mode.

Any one has any idea? Thanks in advance and sorry for the wall of text.

Edit: MGAdt here
Diagnostic Report (1.9.0027.0):
-----------------------------------------
Windows Validation Data-->

Validation Code: 50
Cached Online Validation Code: 0x0
Windows Product Key: *****-*****-*****-*****-HYRR2
Windows Product Key Hash: W5/6nm6F2UPXrCkY5xUhXb/+21g=
Windows Product ID: 00426-OEM-8992662-00006
Windows Product ID Type: 2
Windows License Type: OEM SLP
Windows OS version: 6.1.7601.2.00010100.1.0.001
ID: {2B96A7AD-B828-4A0D-BE46-9C0076FE8223}(1)
Is Admin: Yes
TestCab: 0x0
LegitcheckControl ActiveX: N/A, hr = 0x80070002
Signed By: N/A, hr = 0x80070002
Product Name: Windows 7 Ultimate
Architecture: 0x00000009
Build lab: 7601.win7sp1_gdr.130318-1533
TTS Error: 
Validation Diagnostic: 
Resolution Status: N/A

Vista WgaER Data-->
ThreatID(s): N/A, hr = 0x80070002
Version: N/A, hr = 0x80070002

Windows XP Notifications Data-->
Cached Result: N/A, hr = 0x80070002
File Exists: No
Version: N/A, hr = 0x80070002
WgaTray.exe Signed By: N/A, hr = 0x80070002
WgaLogon.dll Signed By: N/A, hr = 0x80070002

OGA Notifications Data-->
Cached Result: N/A, hr = 0x80070002
Version: N/A, hr = 0x80070002
OGAExec.exe Signed By: N/A, hr = 0x80070002
OGAAddin.dll Signed By: N/A, hr = 0x80070002

OGA Data-->
Office Status: 109 N/A
OGA Version: N/A, 0x80070002
Signed By: N/A, hr = 0x80070002
Office Diagnostics: 025D1FF3-364-80041010_025D1FF3-229-80041010_025D1FF3-230-1_025D1FF3-517-80040154_025D1FF3-237-80040154_025D1FF3-238-2_025D1FF3-244-80070002_025D1FF3-258-3

Browser Data-->
Proxy settings: N/A
User Agent: Mozilla/4.0 (compatible; MSIE; Win32)
Default Browser: C:\Program Files (x86)\Google\Chrome\Application\chrome.exe
Download signed ActiveX controls: Prompt
Download unsigned ActiveX controls: Disabled
Run ActiveX controls and plug-ins: Allowed
Initialize and script ActiveX controls not marked as safe: Disabled
Allow scripting of Internet Explorer Webbrowser control: Allowed
Active scripting: Allowed
Script ActiveX controls marked as safe for scripting: Allowed

File Scan Data-->

Other data-->
Office Details: <GenuineResults><MachineData><UGUID>{2B96A7AD-B828-4A0D-BE46-9C0076FE8223}</UGUID><Version>1.9.0027.0</Version><OS>6.1.7601.2.00010100.1.0.001</OS><Architecture>x64</Architecture><PKey>*****-*****-*****-*****-HYRR2</PKey><PID>00426-OEM-8992662-00006</PID><PIDType>2</PIDType><SID>S-1-5-21-3861901113-1827051978-3078661920</SID><SYSTEM><Manufacturer>System manufacturer</Manufacturer><Model>P5K SE</Model></SYSTEM><BIOS><Manufacturer>American Megatrends Inc.</Manufacturer><Version>0901   </Version><SMBIOSVersion major="2" minor="4"/><Date>20080102000000.000000+000</Date></BIOS><HWID>3F223307018400FA</HWID><UserLCID>0408</UserLCID><SystemLCID>0409</SystemLCID><TimeZone>GTB Standard Time(GMT+02:00)</TimeZone><iJoin>0</iJoin><SBID><stat>3</stat><msppid></msppid><name></name><model></model></SBID><OEM/><GANotification/></MachineData><Software><Office><Result>109</Result><Products/><Applications/></Office></Software></GenuineResults>  

Spsys.log Content: 0x80070002

Licensing Data-->
Software licensing service version: 6.1.7601.17514

Name: Windows(R) 7, Ultimate edition
Description: Windows Operating System - Windows(R) 7, OEM_SLP channel
Activation ID: 7cfd4696-69a9-4af7-af36-ff3d12b6b6c8
Application ID: 55c92734-d682-4d71-983e-d6ec3f16059f
Extended PID: 00426-00178-926-600006-02-1032-7601.0000-1932013
Installation ID: 020566899941533226970724113823504425546181360012188384
Processor Certificate URL: 
Machine Certificate URL: 
Use License URL: 
Product Key Certificate URL:
Partial Product Key: HYRR2
License Status: Notification
Notification Reason: 0xC004F057.
Remaining Windows rearm count: 4
Trusted time: 12/7/2013 10:08:41 μμ

Windows Activation Technologies-->
HrOffline: 0x00000000
HrOnline: 0x00000000
HealthStatus: 0x0000000000000000
Event Time Stamp: 5:31:2013 22:55
ActiveX: Registered, Version: 7.1.7600.16395
Admin Service: Registered, Version: 7.1.7600.16395
HealthStatus Bitmask Output:


HWID Data-->
HWID Hash Current: OAAAAAEABgABAAEAAAACAAAAAgABAAEAln3IPHcWdOaI/QaeGlI++gKlZD6wmYqbXKNYK1R0zDE=

OEM Activation 1.0 Data-->
N/A

OEM Activation 2.0 Data-->
BIOS valid for OA 2.0: yes, but no SLIC table
Windows marker version: N/A
OEMID and OEMTableID Consistent: N/A
BIOS Information: 
  ACPI Table Name   OEMID Value OEMTableID Value
  APIC          A_M_I_      OEMAPIC 
  FACP          A_M_I_      OEMFACP 
  HPET          A_M_I_      OEMHPET 
  MCFG          A_M_I_      OEMMCFG 
  OEMB          A_M_I_      AMI_OEM 
  OSFR          A_M_I_      OEMOSFR 

The reason why you get the message is, that you use an Acer OEM key (Partial Product Key: HYRR2) on a system without OEM/SLIC 2.1 marker in the BIOS.

You use an Asus P5K SE, so the seller of the PC installed a cracked Windows 7 Ultimate and MS detected the crack now and flagged the Windows as "non genuine".

So, buy a genuine license from Microsoft if you want to use Windows.