I just downloaded the latest ArcGIS Earth version 1.2.1 and installed it on a Dell 8700 with i7, 6 GB ram, 1 TByte drive, and NVidia GeForce GTS 240 graphics card running Windows 10 Pro 64bit. When I start ArcGIS Earth it comes up, but I am unable to interact with it and the UI completely freezes on the machine. The only option is to reboot. After a couple of times doing this, I started the task manager before starting ArcGIS Earth and watched the resources. The disk activity climbs to 80% (not sure what is going on with that), and the CPU is at about 20%, with ram at about 2.0 GB utilization. I cannot poke around when ArcGIS Earth is running, since it locks the UI completely.