Unity editor doesn't work

Since a few days I’m fighting the following problem:
When I open a project in my Unity 5.1.0. I can only work with one scene in it. If I want to work with one of the others the program crushes. Always! (Only exception: this one Scene). There’s also always a popup that the unity editor doesen’t work before unity closes. This occured suddenly; I didn’t change anything (intentionally). I did already uninstall and reinstall Unity… didn’t work :frowning:
Can anyone help? It would be great if I wouldn’t have to recreate all these scenes/levels!
Thanks in advance!

That happend to me. I just had to redownload it.