Answer by lexluthor

I hate to speculate but perhaps it's only nagging because I installed it on C: first, where it infused its SSL certificates, and then tried to install it on another drive where those certificates were unavailable--on my Z: drive. Anyway, at least for me, the problem stems from the program insisting on being installed on the C: drive. It installed fine when I finally tried to just re-install it on C:.