I can’t favour on Windows Defender even though I don’t have any other AV software installed.
Did you ever use Spybot? Sometimes remnants of Spybot may cause a problem…
Go to Security and Maintenance, look in ‘Security’ and see what program is listed under Germ Protection. Windows Defender will not be enabled if there is a program other than Windows Defender listed.
Run the McAfee Removal Gizmo again and once again restart the computer after using it.http://service.mcafee.com/FAQDocument.aspx?id=TS101331
For further information see the reply of quietman7 in http://answers.microsoft.com/en-us/protect/forum/protect_defender-protect_scanning/windows-defender/e994f94f-92d5-4d44-9721-79c2a686ce24
Was this a new Windows 10 computer with McAfee preinstalled or was this an advance from Win 8? Has any other AV program been used on the computer? If so imply you run the removal gizmo(s) for those programs. List of
anti-malware product removal tools