I note that PI has some bugs when using Concatenate Image | Mosaic. (GRD files)
I have a 3x3 grid of images. If I add the first 3 images in X direction (0,0) (1,0) (2,0) PI will mosaic the images. If I add the second row (0,1) (1,1) (2,1) and try to mosaic the 2x3 grid, PI will stop working with message "A problem caused the program to stop working correctly" etc.
I thought I had read that this was fixed, but since this is version 1.2.2.1984, doublethink will be applied.
Gareth