switch to mental ray and then create your IPR frame again
the smooth preview is a render time smoothing which software renderer can't do
each time you change the smoothness preview, though, you have to redraw your IPR frame
that's a "Ch" pronounced as a "K"
Computer skills I should have:
Objective C, C#, Java, MEL. Python, C++, XML, JavaScript, XSLT, HTML, SQL, CSS, FXScript, Clips, SOAR, ActionScript, OpenGL, DirectX
Maya, XSI, Photoshop, AfterEffects, Motion, Illustrator, Flash, Swift3D