I have now managed to use Photomerge Exposure on 2 images.
The best tip I have had is to reduce the Pixel Size of the images and that does work even on the same original but different files/images. I am therefore guessing it is a RAM size issue and 3GB isn't enough for this product. If this is the case can I suggest you test the software on a machine using 3GB of RAM. The process will run but only on reduced Pixel size and that isn't good for my useage.
The correct answer to Photomerge crashes etc. is to reduce the Pixel size from 6000/4000 to 2400/1600. I suggest that it easy to reduce size of image using PAINT or similar. I believe the problem is entirely down to lack of available RAM and 3.00 GB physical memory is just not enough to run Photomerge successfully, especially as other Apps may be using available RAM at the same time. rupalia98692837