Unity Settings To Prevent Jittering?

Hello and thanks for the help!

I have a default cube that's jittering when it moves across the screen. There is only one script in the entire scene: public Rigidbody2D rigi; void Start () { rigi.velocity = new Vector2 (10, 0); }

That's the entire "game" right now, and the cube is jittering like a leaf on a tree.

The cube has a frictionless material as does the cube that it's sliding on top of. There is nothing else moving in the scene - the camera is completely static. There are no calls to Update(), FixedUpdate() or what have you. I've tried many fixes, including screwing with VSync, turning off all other applications (including MonoDevelop) and other obvious solutions, and I cannot isolate what the problem is.

I'm willing to try anything at this point. Thank you very much for your help. If it means anything to you, I'm on a Late 2015 iMac.