Whelp, it got so bad, I couldn't even get it to boot into anything but safe mode. So I restored from a checkpoint earlier in the month, and then re-applied the various updates. Working properly now. Not sure what caused the corruption.

Side note: They made it horribly difficult to boot into safe mode with win10. No more holding down a button on the keyboard during boot. You have to fail to start windows 3 times in a row, and then "just know" the byzantine things to click on to finally get it to reboot into safe mode. Thanks MSFT.