I have 2 printers, 1 delta running on an old core2duo, 6GB Ram, Win7 home, GFX Ati Radeon 2600xt. 1 cartesian I5 , 12Gb Ram, Win7 home, Nvidia GTX560. Both have the latest gfx drivers and does not show this bug in 3.1.1 Sometimes after opening "about simplify3d" the screen does not refresh...