Microsoft has been getting a lot of stick for updates breaking the Windows 10 experience: this one broke Windows Defender.
Windows Defender was recently boosted by an industry-respected AV Test report that gave it a perfect rating. This was excellent news for both Microsoft, which has been working hard to make Defender a top-notch security offering, and users who can get the best protection out there without splashing the cash. Until that is, Microsoft went and broke it with an update.
