From LedHed's Wiki
Windows system files are owned by the user "TrustedInstaller".
Sometimes you want to edit a system file, but in order to do that you need to take ownership of that file. That is fine, but when you're done editing the file how do you change the owner back to "TrustedInstaller"?
Its quite simple, just go to the file/folders security properties and take ownership but instead of putting your user account or the administrator account use:
NT SERVICE\TrustedInstaller
Problem solved!