Thanks Oshyan,
That was interesting, uncheck images and it works fine.
On previous testing I concluded that it was crashing when it reached EU2, or Flowers1, but when I scanned those folders in isolation it worked fine.
I don't actually need to scan the images, I just wanted to have the previews, so that solves the issue for now, although it is obviously something that ought to be fixed.
Thanks for helping me find a work around.
Charles