Huh, I didn’t think that a clean install would help (you know the typical Microsoft “reinstall Windows” joke :-/ ), but after uninstalling it, and also running the separate uninstall executable, rebooting, reinstalling from scratch, it appears to be working now.
I also reinstalled only a minimal set of features (just the ones I use the most, including the firewall), so that might have done something.
In any case, it’s working again, so hooray. 
