Ok, I've figured out what's going on and have solved this.
For anyone else with the same problem, try this:
1. In the 'Resources' folder, I had another Resources folder.
I thought that Kontakt 5 may not have been able to navigate into both Resource folders.
So I cut the contents out of the second folder, and placed them into the first one, then deleted the second folder altogether.
This then displayed the actual instrument pictures once one instrument was loaded into Kontakt 5 - ie: Violins - the Violin graphics appeared, as did all other graphics - but still not the dark green background image.
2. I then clicked on the wrench icon at the top left of the loaded instrument, and then 'Instrument Options' - and there was the problem.
In the 'Instrument' category, there was a entry called 'Wallpaper' but it's content read *none*.
I clicked 'Browse' beside it and navigated to the 'pictures' folder in the 'Resources' folder, and loaded the appropriate image, which for Violins, Violas and Cellos, is the main .PNG image of 4 spotlights.
For the Basses, there is a second .PNG image beside it, showing only 2 spotlights, because only 2 Basses will load in.
3. I then re-saved each instrument.
That's what worked after closing and reopening Kontakt 5 and after a computer restart as well.
Hope that helps the next guy, if there happens to be another who faces this.
Yay! Now give the fat kid another doughnut - or something for his efforts - and so he'll stop talking for a little while as well.
