Sorry for the delay in replying. This had me totally and utterly stumped!
The problem turned out to be that you don’t have the width set to 1000px at all, you have it set to 1000%! Untick the box which says ‘Width as %?’ and your problem will be solved.
I need to write a bunch of fixes in to prevent this type of thing happening. I’ll be rewriting much of the template generator in a month or so and I’ll hopefully fix this problem then.