It's the progress bar down on the bottom left of the screen. It says that it is writing before it actually renders!
I am asking a lot out of my system, I am rendering big in ultra & 300dpi.Also lots of reflective materials with are making a 3200 pixel image guess at around 72hrs to render.
This is the biggest render size I have managed to get so far without the hiccup occuring.

Cheers for your help!

Regards Rokol.