thanks you both so much. with some help from Nikon Asia, Mongo has put through a clean up utility and reinstalled the test version (2.7.4). It is working but it had a funny little turn to its old defect momentarily. So, Mongo moved all the images on the desktop to elsewhere (as it seeks all the problems began when it tried to access the desktop images) just in case it was some kind of linking problem it had with desktop files. It now seems to be working normally and accessing all image files including the ones moved from desktop. Mongo is still not sure about it and is quite anxious to know it is working properly and for good this time. He should know over the next few days.

Davsv1 - Mongo will try the exercise you have indicated also and will do so from time to time.

With Mongo's old PC, it was easy to "clean it out" now and then of all temp files and the like. Still have not worked out how to to do the equivalent of that exercise on this Mac but hopefully will eventually.

thanks again guys and sorry for the panic.