You'll need to backup your files and do a PC Refresh or clean OS install - it seems this as a bug that MS have still not fixed
Yeah, there seems to have been an issue concerning Defender connected to the last update. Several people have had similar problems & in those cases, it looks like a refresh or repair install solves the problem.
Repair Install Windows 10 with an In-place Upgrade - Windows 10 Forums
If you're having problems with Windows 10 on your PC, you could use push-button reset to refresh or reset Windows.
Refresh your PC Fixes software problems by reinstalling the OS while preserving the user data, user accounts, and important settings. All other preinstalled customizations are restored to their factory state. In Windows 10, this feature no longer preserves user-acquired Windows apps.
Reset your PC prepares the PC for recycling or for transfer of ownership by reinstalling the OS, removing all user accounts and contents (e.g. data, Classic Windows applications, and Universal Windows apps), and restoring preinstalled customizations to their factory state.
Bug for sure. I researched problem and never did find a fix. Don't think Refresh would work. I did a clean install. No problems at all. He already had all his files saved and program disks.
I found other problems that might be related MSE also. I found 2 files left in another directory that could not be removed, with cardfile in name (MS Wallet I think or something related to credit cards).
You might have to download the Windows 10 1511 ISO (https://drive.google.com/file/d/0Bwt...ew?usp=sharing). When it is done downloading, run setup.exe and then when you get the screen before install (The one were you choose what to keep), select, change your settings, and select keep nothing. Hope it helps
I did a clean install which took care MSE problem. I work on many PC's. No problem with ISO. I download both Windows Pro and Home 32&64. I burn each version to DVD and save all 4 ISO to usb stick just something happens to DVD.
I was worried when Microsoft Pulled back 1511/10286. So I asked Microsoft if ISO would be different but got only standard canned replies. No answers.