I know that a system update might solve this problem, but this is really unbelievable. I thought Notepad should be something fundamental and solid—something that would never fail me on Windows.
As an aside, I really like the stereogram on that page. The background seems designed for the purpose, so the edges on the 3D object are actually outlined, rather than the general kind of stereogram where you just get the texture randomly applied to the object.
Now it's not.