Resolution:
Description:
=========
The full stack is:
java.lang.NoClassDefFoundError: Files
Caused by: java.lang.ClassNotFoundException: Files
    at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
Could not find the main class: Files.  Program will exit.

Environment:
=========
BE 5.1.0 on Windows 7

Symptoms:
=========
No changes were reported in the environment.

Cause:
=========
Problem solved when a third party jar jt400.jar was removed from the build path.

Resolution:
=========
This type of error is thrown by the UI when it tries to load a class in a missing jar file.  The jar file may had been changed in the enviroment.  The .beproject should also be checked for merge errors.