xbrit: the problem was my AH installation was version 2.17 or an even earlier one. The install files don't come with the custom maps.
I managed to do as you suggest but with a map dated 10 months later than the screenshot. Here's the same area (see below). The problem is with all the terrain changes and developments at the time, there is a small chance that the wrong map could be crashing my film viewer. Maybe.