Here's some more notes:
I decided to delve into the code a little bit to see if I could find your orbit rate variable (sMod) and played with it a little... I slowed down the rate of orbits considerably (sMod=1.2) which made it a lot more playable in terms of using your seedlings.
But still, as anikk has pointed out in several of his level's threads, it opens up many cans of worms when you have plantable moving planets. I don't think the problems are insurmountable, I think it is just very difficult to get all the motion parameters set so a moving planet is fully usable. Seedlings, flowers, and mines all move at different rates of speed and it will be a very challenging task to get all the orbits set so you don't get any harmonics where stuff gets stuck.
I noticed that the game crash comes when your seeds arrive to attack the large outer planet on the right, perhaps when they breach a tree and start infecting the center.
I'm curious about why you made the game map and some of the send distances so massively huge... after you take an asteroid on the outer ring you can zoom the game map out really, really, really far until most of the asteroids are just little dots.
I also (for the first time in any level) noticed one other very interesting side effect of having moving planets with trees: when you attack a moving planet and your seedlings start infecting tree roots, the seeds' motion along the root path is affected by orbital motion such that the infecting seedlings can be brought to a complete stop if the orbital vector is greater than and opposes their speed along the root path towards the center. But since the asteroids in this level all follow circular paths, the seedlings do shake loose eventually... I thought that was really neat actually.