hmmm weird DIAB....I haven't had that happen before. Provided though that I haven't really used the dropship one all that much.
Anyways I do know one thing Aro could add to this tutorial that would make for better maps and more complex triggering. As I am pretty sure it is possible to do with the use of attaching a trigger to another trigger and that such.
The thing he could add would be something along the lines of this:
1)Dropship comes and lands
2)Units unload
3a)Units follow this path
3b)Dropship follows this path
I myself will look into this more as it would allow for cooler better options for mappers rather than just a simple dropship trigger.