Windows 8 Win8 lost activation (even though I own an original key)

Ok thank you guys, I might be closer to the solution.
I succeeded in installing all updates.

Anyway, win8 keeps not activating. So, I found on the internet that there is a command "slmgr" which deals with win activation. I tried "slmgr /rearm" which should try to reactivate win, but it says: Error: 80070422. I found out that this error is linked to Software Protection Service which may not be running. So, I executed C:\Windows\system32\sppsvc.exe to reenable it, and it says: "sppsvc: bad image. guard64.dll is either not designed to run on windows or it contains an error. [...] Error status 0xc0000428".

So I guess that's it. This dll is most likely damaged, and it should deal with the activation problem.

New updates: I found out that guard64.dll is linked to Comodo AntiVirus. I completely removed Comodo, and now sppsvc does not give that error anymore. Anyway, its service won't start. It is set on "disabled" and there is no way I can set it on "automatic" start. Everything is grayed.
I think starting this service would solve everything. But I can't edit any setting in sppsvc service config. I even tried in safe mode, every option is always grayed and disabled. (Clearly if I do the same thing on other services I can change configs without problem). It seems to me a privileges issue, but I am admin of the machine.

New updates2: I manually set the service start type in HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\sppsvc to Start=2, rebooted, and now the service starts!!
Windows finally is activated!

Thank you very much!