1. Version: W10 
2. Unmodified Cairo Green-Blue. Haven't tried others. Will, try that.
3. While I have Groupy running, I generally don't have anything grouped.
4. It's not reproduceable, that I've found, and it's not fast. Just after a few days Windows Explorere will just break. Sometimes I can restart it from task manager; sometimes it doesn't show up and I have to reboot. (I don't *think* I've seen it fail when I was actively using it, so may be sleep related, backup related,
In addition to that, I'm running two physical windows, and from Stardock I'm running CursorFX (Fluent), Curtains, Fences and Groupy. No other O/S mods other than a server connector...non-domain.)