Unity 5.5 Project Files Crash Unity

Strangely, whenever I attempt to open the Unity 5.5 version project files for the book, everything loads fine before the crash dialog appears.I have to completely remove the project’s library files to get it loaded successfully but then everything in play mode simply slows to a crawl, hardly moving at all in a very jittery manner. I’ve experienced none of these problems with the older project files for Unity 5.4 running inside Unity 5.5. I’ve lost the older version due to an emergency system restore - if there is no known solution to the current issue, can I somehow obtain a copy of the older Unity 5.4 version of the book’s code files?