I've had the exact same issue only without a postprocessing shader. I have a secondary view with its bmap property set to a TGA image file. The image is then displayed in a panel. (Sort of like the rearview mirror concept.) The same problem you're reporting occurs in the secondary view even though it doesn't occur for the camera view. Also, the problem only seems to occur on NVIDIA cards. I haven't seen it on any of the ATI cards I've tested on. As MrCode suggested, the problem goes away if I turn off antialiasing. Hopefully some of this info might help Conitec to pinpoint the root cause. Or does Conitec already know what's causing this problem or when it might get fixed? (Or if there's a better work-around than removing AA?)