I kept getting this very annoying message on startup."This program has been turned off". Well, yeah. I turned you off. Why do you need to tell me?
Well, like a bad girlfriend who stalks you, you want to find a way to get rid of her.
It turns out in my case, the stupid thing was being launched still on run.
Here are the simple steps, lifted from a friendly MS forum by Dalv49. (Gotta give props)
1. Launch regedit (Win+R, type "regedit", hit return)
2. Locate the Key HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRun
3. Delete Value "Windows Defender"
note: could be a good idea to check "HKEY_CURRENT_USERSoftwareMicrosoftWindowsCurrentVersionRun" as well
You can also just run MSConfig. My favorite handy startup killer. Less work. Point and click.
Happy Coding!, errr. Disabling.