Hi Elied
On more exploration of the missing files - I found that in fact the files are not missing when go to "All Photographs" option within lightroom. So they are not missing. It seems that when I export files to my desktop Lightroom adds the exported photo to my catalog.
My question is how to stop this . Also what dictates that the exported files shows or does'nt show up within Lightroom?
Sue
When you choose to "Export" (in the Library module), there are several options that you can set. One of them, under "Export Location" is a check box for "Add to this catalog." If checked, the exported files are added to your catalog. I think checked may be the default, so in the Presets that I use I have now unchecked this box, and that seems to fix it.
Before I noticed that check box, I, too, was wondering why every exported image was duplicated in my Library. Now it doesn't happen.
I hope this helps.