Hi, was editing a Canon G12 raw file today in ACR, sent it to CS5 as a smart object and it turns up with what looks like over-lapping mesh, horizontal and verticle lines of varying thickness, and dark grey in color, in the shadows. Never seen it before, but it disappeared when I flattened the file. If I overly darken it to the point of complete black, the lines become very regular, thin ones inside a pattern of thicker ones covering the whole file.
Any ideas what it is or what caused it