My Maya installation worked perfectly. It is not my computer. Something caused it to stop working overnight, somehow.

When I try to drag a vertex or something like that, it moves the vertex, but then I have to click like 3 times somewhere outside the mesh before the actual mesh will catch up and follow the vertex. Until I do that, it just stays as it was, with a floating vertex somewhere inside it or outside it. It makes modeling borderline impossible and completely infuriating.

What ought to be happening is what we're all used to-- as I move the vertex, the mesh follows it actively, so I can see what it looks like at every given moment until I release the vertex in its new position.

Other weird thing: this only applies to complex meshes, like a couple thousand faces. A simple cube works fine.

What gives?? Anybody?