So I've got a really weird problem. I had just discovered that arches and cylinders always snap to the grid, which of course makes manipulating them a lot easier than I had thought, so I thought I'd try making a simple spiral staircase with a smooth underside. After a lot of messing around with vertex editing, I had something that looked perfectly fine in Hammer but, when I compiled, suddenly broke up into a jaggedy surface, thusly: And I'm like, WTF mate? All four corners of each step line up with the grid just fine, so it can't be that. (And yes, I did turn the steps into func_details, not that it's relevant.) And there's no unusual slowness to the compiling process or errors. So what is causing the compiler to choke on the coordinates of the steps so badly?