So I've deleted everything I can find to do with SL. I've updated the Flash. I've re-started and zapped my P-Ram. Re-installed the SL viewer and when I double click the icon it briefly appears in my doc bounces for a second or so then disappears.
I've just logged in on my Macbook pro and that's working. Hmmm...
I know the issue isn't sorted yet but thanks to all that are trying to help !