Flash "corrupting" all tweens, so I'm left with objects popping around

Anyone experienced this? I send an SWF of a Flash game to the client, and they say all the animations are gone. They send it back, and sure enough, there are no animations. It’s like it got rid of every tween. I’ve re-exported it and sent it again, and sure enough, blegh, it comes back in epileptic seizure mode.

It works until the client sends it back to me. Anyone know how to fix it?