Windows 10 hosts file used by another process

There are a few other question with this same title but they do not solve my problem, so I am opening another one.

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  I have set the permission for the "hosts" file to full access for the current user. I have even taken the ownership. Current user is in Administrators group.

  
  


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  I have turned off UAC.

  
  


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  I have removed read only permission from the file.

  
  

  C:\Windows\System32\drivers\etc>attrib hosts
  A            C:\Windows\System32\drivers\etc\hosts
  



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  I have disabled my Panada Antivirus. I have also stopped 3 panda services from Services palette.

  
  


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  I open an elevated Command Line (run as Administrator). Run Notepad and change the file. When I try to save the file I receive the following error:

  
  

  "The process cannot access the file because it is being used by another process.

  
  


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  I check the file using "Unlocker" and the software says there is no active lock on the file.

  
  

Can anyone help?

Answer

I could eventually find the culprit. It was a program called "Tiny Firewall" (a windows firewall rule management software) that caused the problem.

I am not exactly sure what does it do to the hosts file because none of the available software could show a lock on the file. I could find that it is somehow involved with the file using process monitor (Sysinternals). I quit the UI and stopped the process (would not allow to stop, killed the process-tree and set to manual service).

P.S.: This is a feature of Tiny Firewall (protection of hosts file) and you can simply turn it off from its settings.