DONT PRESS ON THE LINK I'VE POSTED BELOW.
Funny, I opened up Safari, opened up Pprune, opened up this sub-forum, clicked on this thread and the screen went blank followed by this link:
Redirect
It seemed to want me to download and update my 'flash' installation.
What the heck is that all about. I closed down Safari and started again and it hasn't re-appeared despite going through the same click sequence.