Thats all, its very simple. I tried to isolate the problem and I found that. Whenever you try to paste a subroutine, the game crashes. It also happens if you open the code with subroutines in it.
Hm, weird, I can paste very complex subroutine rules and game modes with many subroutines without problems.
Edit: Ah, Altimor appears to have found what exactly causes this: