I've been having this problem at least once every two months. I'm 100% sure it's related to Avast. I use Avast premier (using the latest version currently). Every time I have this issue, I reinstall Avast, and it fixes the problem, a while later...It reappears.
However, on my other systems where I'm not running Avast, no problems. I admit, this does happen to certain users who don't use Avast. But in my case, and probably a lot of others here, it actually seems to be Avast causing the problems. I'm not sure why other non Avast customers get it, that's probably related to some other software they're using.
Can someone look into this and sort it out? It almost always happens when Avast has a update to the actual software, definitions is usually fine. It really sucks that Windows 10 has been out for so long and Avast is still causing problems, looking at CCleaner. Avast isn't doing a nice job messing up the registry either.