Microsoft has released a new update for Windows Defender that has broken both the Quick and Full antivirus scans. When users use these scan options, Windows Defender will only scan approximately 40 files. Users can still perform a Custom scan and specify the drive they wish to scan for viruses. Microsoft has told BleepingComputer that the issue has now been resolved in “Security Intelligence Update for. Windows Defender Antivirus – KB2267602 (Version 1.301.1684)”” definitions. For Windows 7
Source: security