这是什么异常？

之前都好好地，怎么现在运行就变成这样了，new这个Frame，会报异常了。
异常内容：Exception in thread "AWT-EventQueue-0" java.lang.NoSuchMethodError: org.jvnet.lafwidget.LafWidgetUtilities.hasAutoCompletion(Ljavax/swing/JComboBox;)Z
at org.jvnet.lafwidget.combo.ComboboxAutoCompletionWidget$ComboBoxPropertyChangeHandler.propertyChange(ComboboxAutoCompletionWidget.java:577)
at java.beans.PropertyChangeSupport.firePropertyChange(Unknown Source)
at java.beans.PropertyChangeSupport.firePropertyChange(Unknown Source)
at java.awt.Component.firePropertyChange(Unknown Source)
at javax.swing.JComboBox.setModel(Unknown Source)
at frame.BackstageFrame.initComponents(BackstageFrame.java:512)
at frame.BackstageFrame.<init>(BackstageFrame.java:25)
at frame.BackstageFrame$17.run(BackstageFrame.java:2916)
at java.awt.event.InvocationEvent.dispatch(Unknown Source)
at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
at java.awt.EventQueue.access$000(Unknown Source)
at java.awt.EventQueue$1.run(Unknown Source)
at java.awt.EventQueue$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.AccessControlContext$1.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)我用的是myeclipse，在写一个很简单的swing的鞋业销售管理系统。界面代码是用插件拖出来的。请问这是什么异常啊？
我通过堆栈信息，看到它指向的是我的jcombobox的setmodel方法那条语句。