“A number of Windows 7 and 8.1 users are encountering problems with Microsoft Security Essentials and Windows Defender. Users are seeing their automatic anti-malware protection turned off without their knowledge and are seeing out-of-date virus definitions.”
Some Windows 7, 8.1 users reporting Security Essentials and Windows Defender problems
“A number of Windows 7 and 8.1 users are encountering problems with Microsoft Security Essentials and Windows Defender. Users are seeing their automatic anti-malware protection turned off without their knowledge and are seeing out-of-date virus definitions.”