Haven't seen anything about this anywhere, so I think I'm going to have to try creating a new local user, disabling sync, and then deleting the original user account, because I'm at a loss.
It's KB3072318. Searching KB3072318 on google shows other people having same problem. Simply uninstall and it would be fine again.. Greets smiler10
Yep, that fixed it, thank you. Shows what I get for assuming it had something to do with my Windows 10 downgrade.