When building for WINDOWS 64bit, after build is complete and launched, build crashes if project was previously on a newer version of UNITY. It seems that when you take the project from 5.5.0f2 to any other version it works fine until you take it back to 5.5.0f2.

Important notes:

1. Project build crashes when executed if it is opened and built in Unity 5.5.0f3 or 5.5.0p1 and then opened and built in Unity 5.5.0f2; -- IMPORTANT--
2. Project build works good when opened and built in Unity 5.5.0f3 or 5.5.0p1 and then opened and built in Unity 5.4.3f1 and vice versa.

Seems that if you open this project in Unity 5.5.0f3 or 5.5.0p1 and then open and build it in 5.5.0f2 the build crashes (shows black window), and then if you try to build it with any other Unity version it does the same thing when build is executed. (When you import this project from Unity 5.6.0a6 it works fine)

To reproduce:

1. Open project in Unity 5.5.0f2 and close it.
2. Open project in Unity 5.5.0f3 and close it.
3. Open project in Unity 5.5.0f2 again.
4. Build A Windows 64-bit build.
5. Open the executable.

The stacktrace hints at the issue being PhysX related.
Project is attached to this letter.