Security disabled without my doing?

[devavictrix]

Today I just happened to notice that Windows defender was turned off. I couldn't turn it back on. Even after logging in as an administrator I couldn't get defender to open or turn on.

In the end I had to make changes to the registry to get it to turn on again.

Could this be caused by any legitimate means? What could have happened that needed me to play about in the registry?

I recently reinstalled Windows and it was certainly working last time I checked...maybe two weeks ago. I use a user account for day to day stuff. Its very rare I login as an administrator. I have next to nothing installed on the computer... Office, VPN software and World of Tanks. I usually use a VPN and have my drives encrypted using Bitlocker.

Thanks for any help.

 

[devavictrix]

Turns out lots of entries in the registry have been changed. Real-time protection included. Looks like im spending the rest of the weekend reinstalling Windows! Or maybe its time to say goodbye to MS Office and World of Tanks and install Linux... if its safer!?

How can this happen? How can you prevent it? I don't use an admin account so I don't understand how the registry can be changed without me entering the password!