Thanks everyone. All good advice. In the end, it was a laptop / Navbox problem rather than anything more general. Peter Mundy is indeed exceedingly helpful.
Reappraisal a couple of days later -- good software, hopefully very useful, although not completely intuitive to use. Slightly disappointing you can't cut and paste bits of routes and a couple of other gripes, but otherwise worth the money. I'd recommend it. Peter says they'll be adding terrain as an update next year.
QDM