Yeah, I'm on Win XP and Firefox, and I don't really intend to change either of those things just to play a Flash game. Not to belittle your work or anything. I'm just kind of comfy in my setup.
The graphics are much more polished than the Cargo game, but the gameplay isn't. There's no reason to make the player drive to the gap each time, or start from scratch if their design fails.
do you use windows 7 and IE? try to change your browser