As others have said
Game froze at level 1, when ever you drop the cargo onto the correct space, the game (For me) freezes. Some graphics/music continue to run, such as the clouds, and the reflection in the helicopters glass, while others freeze along with the game, such as the rotors.
The menu button in the top right still works and brings up the pause menu, and allows you to restart/level select/title screen, however the 1st level then only brings up a black screen.
I'm using the latest firefox, with Windows XP
Shame, as it controls well, and might have been a fun game. Hope you fix it