Those claiming Defender is on by default may want to double check because that is what I read as well, but it wasn’t. So either a virus turned it off or it was never on by default. I personally feel that windows 10 saw McAfee on my system and therefore did not enable Defender. Only problem is I was not using McAfee and even if I was it is not compatible. I now have Defender turned on and scanning, it is taking forever to do a full scan! Microsoft doesn’t even make a registry cleaner, those don’t really work and will most likely just screw things up, I assume Combofix is a registry cleaner. 6 hours later my scan is about 2/3 done.