Could you try "do nothing" in the Post-Processing section and see what happens. Check to see if the folder is created on the Desktop after the exported process has been completed.
Before you exit Lightroom make sure the export process has completed, you can monitor this process from a popup in the top left corner of the Lightroom dialog window.
Double click on the folder to view in Finder. The export process does not complete very quickly as a save so you expect between 3 to 5 seconds for each file you have selected to export since the original file has to be rendered and apply all the edits.
That's how I had it earlier... anyway I restarted my computer for the third time and now all the photos are visible where the should be! YAY !! thanks for your help everyone. hopefully this is resolved.