Blender crashes and wiggly animations dissappear

Hello. Yes this is usually how things go with software’s, we have to course correct, adapt and find solutions. It’s never a smooth sailing. But what’s life without a few challenges, right? 

I’m guessing the physics are gone because the cache goes away and have to be re-baked. Blender crashes just because Blender crashes from time to time, specially if there’s an addon involved. I guess one thing you can do, if you’re not doing it already, is to download the same Blender version as the teacher so the version of the addon matches as well and it may be less buggy.