I couldn't see any spheres at all so I was confused by your comment, which led me to realize WebGL wasn't working, which in turn reminded me I had disabled hardware acceleration in Chrome long ago because of some bug which made browsing unbearably slow. I've now re-enabled it and it seems the bug has since been fixed. So, thank you!
It’s the forced graphics card switching that causes system crash in every 20th case.
Same, you can also drag them around to a new rotation.