JMeter Could not initialize class org.apache.jmeter.gui.util.MenuFactory

Why??? It worked yesterday, why does JMeter not work properly today. Where is my right-click menu?

This is the error I was getting at the console after opening jmeter.bat:

Uncaught Exception java.lang.VerifyError: class com.google.common.collect.AbstractMapBasedMultimap overrides final method setMap.(Ljava/util/Map;)V. See log file for details.
Uncaught Exception java.lang.NoClassDefFoundError: Could not initialize class org.apache.jmeter.gui.util.MenuFactory. See log file for details.

Uncaught Exception java.lang.VerifyError: class com.google.common.collect.AbstractMapBasedMultimap overrides final method setMap.(Ljava/util/Map;)V. See log file for details.

Uncaught Exception java.lang.NoClassDefFoundError: Could not initialize class org.apache.jmeter.gui.util.MenuFactory. See log file for details.

The reason was because I had put a new version of Selenium in the apache-jmeter-2.8\lib\junit folder which was needed to support a new version of Firefox. What I hadn’t done was remove the older version.

Deleting the old version and restarting JMeter allowed it to start up without errors, and my menus are back.